A Severely Specialized Store is a retail outlet that only deals with an incredibly narrow product range, typically one or two items of a very specific type. As this trope is almost always invoked due to Rule of Funny, the store's products will be exactly what the protagonists need in their moment of crisis (unless it's closed when they get there). How such a business manages to stay in operation, or why the heroes can't just go to a general-purpose merchant, is never raised.
An infrequent variation is the inverse of this trope — a store that sells everything except for one thing, typically what the protagonists need to solve the current crisis.
Also see Crippling Overspecialization, The Magazine Rule. Contrast We Sell Everything.
This is a recurring joke in some of Robert Munsch's children's books. Zoom! starts with the protagonists visiting a wheelchair store (an obvious Expy of a car dealership), while Smelly Socks includes a trip to the city's socks store, which is so large it can be seen from the river.
Mr. Ollivander of Harry Potter sells wands. Just — wands. Justified as each wand must fit its owner, much like a shoe or clothing store. Wands are also major purchases, as a wand does not appear to ever 'wear out', and since they are central to a wizards power, it is worth buying the highest quality you can afford. A wand store is basically a place that sells a product that must fit like a suit, is as expensive as a car, and important as a home.
A great deal of the Wizarding shops seem to be this way, and all are rather justified. Potage's Cauldron Shop sells nothing but cauldrons, and Scrivenshaft's is a borderline example, selling almost nothing but quills.
The Discworld novel Going Postal has Dave's Pin Exchange, which sells only pins (pin collecting serving as a parody of stamp collecting), with the owner being very adamant that he doesn't sell nails. However it's later expanded to Dave's Pin and Stamp Exchange, and by Snuff is Dave's Pin, Stamp and Smell Exchange. (Don't ask.)
Douglas Adams' non-fiction book Last Chance To See recounts his befuddled trip through several of these.
Inverted in Captain Underpants and the Wrath of the Wicked Wedgie Woman: To help Captain Underpants regain his powers, George and Harold need to get some fabric softener to counteract the spray starch that removed them. They run to a new store that opened nearby, which turns out to be "Everything Except Fabric Softener."
The store for all your non-fabric-softening needs!
In an episode of Northern Exposure, Shelly is interested in going to the Mall of America; she mentions that they have a whole store that's just socks. (This is true in Real Life. It's called "Just Socks.")
A variation appears in a skit from All That, with a retail store that sells only a single pair of pants.
Pixelface has an episode where the other characters enter Clairparker's game to do some shopping at the mall. Riley and Romford are looking for sausages and a remote control, respectively. They find everything they are after at a store called 'Sausages n' Remote Controls'.
On early episodes, there was a series of sketches detailing "The Scotch Boutique", which sold nothing but varieties of Scotch Tape. Apparently, while somewhat of a failure when the store first opened, it apparently started doing major business when a new shopping mall opened up, and all the other local stores needed the tape to hang up their "Out Of Business" signs.
Played with in the "Cheese Shop" skit, with a store that sells nothing but cheese... only they don't.
Customer: Have you in fact got any cheese here at all.
Owner: Yes, sir.
Owner: No. Not really, sir.
In "The Cycling Tour". Mr. Pither keeps catching his pump in his trouser leg and crashing. At a small village:
Pither: Excuse me, madam, can you tell me of a good bicycle shop in this village, where I could find either some means of adapting my present pump, or, failing that, purchase a replacement?
Old lady: There's only one shop here. (points to a shop with large signs reading:'BICYCLE PUMP CENTRE. SPECIALISTS IN SHORTER BICYCLE PUMPS', 'SHORT PUMPS AVAILABLE HERE', and 'WE SHORTEN PUMPS WHILE-U-WAIT'
Incredible Crew has the Shorts and Spoons Superstore which sells only shorts and spoons ("No pants! No forks! And you have to buy one of each!")
Among the many strange prizes to be on The Red Green Show's "Possum Lodge Word Game", there was once a coupon for "Tinsel Town: the only store that sells only tinsel all year round."
A Zits Sunday strip features an establishing panel of the inside of the local mall; stores named Just Burlap, Wineglasses in an Hour (a parody of Glasses in an Hour), and Things That Start with Q can be seen in the background.
A common staple of roleplaying games where a store sells magic spells or gear so ridiculously powerful that only a very rich legendary hero could buy or use them.
This is a recurring gag in Axe Cop. Need an awesome ramp to drive to the moon? Go to the awesome ramp store. Unicorn horn? Can be found at the unicorn horn store.
The Order of the Stick has the Polearm Shop. More general armories are also shown, but one strip has Roy go to a Polearm Shop. It's a reference to the "Cheese Shop" sketch, so not only is the shop overspecialized, it doesn't actually have any polearms at the moment.
Though not given any particular focus, Teen Girl Squad has Manolios Ugly One, who likes to advertise his store which specializes only in selling used and broken electronics such as a broken VCR and smashed tape.
Spike: But the store is called Quills and Sofas! You only sell two things!
Davenport: Sorry, junior. All outta quills 'til Monday. (beat) Need a sofa?
In Jimmy Neutron, Retroville has stores like Cheese World, Mime World, and Rug World. Rug World actually had something Jimmy needed to defeat the evil pants.
This was a common gag on Tom Goes To The Mayor. Tom opened a store called "Big Cups", which only sold big cups. There was also a store that just sold bear traps.
Two bear trap stores to be exact. Next door to each other. Owned by rival twin brothers both played by Jack Black. It makes sense they both managed to stay in business due to the lunatic mayor twisting Tom's child safety plan into "let's set ten thousand bear traps all over town."
Ned Flanders once opened up and maintained a "Leftorium" store for left-handed products for left-handed people. It was initially a bust, until Homer Simpson started feeling bad for enjoying Flanders' misfortune and scrounged up as many left-handed customers as he could.
Truth in Television: A shop of this type called Anything Left Handed has existed in London since 1968. The writers may not have known this, though.
When Homer wanted to buy a hammock:
Hank Scorpio: Uh, hi, Homer. What can I do for you?
Homer: Sir, I need to know where I can get some business hammocks.
Hank Scorpio: Hammocks? My goodness, what an idea. Why didn't I think of that? Hammocks! Homer, there's four places. There's the Hammock Hut, that's on third.
Hank Scorpio:' There's Hammocks-R-Us, that's on third too. You got Put-Your-Butt-There.
Hank Scorpio: That's on third. Swing Low, Sweet Chariot... Matter of fact, they're all in the same complex; it's the hammock complex on third.
Homer: Oh, the hammock district!
The "Just Crichton and King Bookstore", a parody of small bookstores overstocking on only the most popular authors, especially those found in airports. The cashier will not entertain a request for Robert Ludlum.
Along some highways in rural parts of Virgina, you can find stores selling cigarettes, hams, pecans, and fireworks. Almost without fail, the store will advertise that it sells at least three of these four things.
In New York, there is a store called "Just Bulbs." They sell nothing but lightbulbs.
As mentioned in the Northern Exposure example above, the Mall of America has a store called "Just Socks," which sells nothing but socks.
Batteries Plus, which does have an enormous variety of said item.
Most malls will have at least one example: one that sells only guitars, or one that only sells candles of all sorts, or one that sells just hats...
Flower companies, whether big and catering only to large orders, or small operations.
Many UK airports and larger railway stations have shops like Tie Rack and Sock Shop, presumably selling to people who suddenly remember they haven't packed properly.
Cinnabon, a chain of stores that sell only cinnamon buns (of a handful of types and sizes), most commonly found in malls and airports. The buns are just that good.
Malls also have another food example of this in the pretzel shop.
And of course, before the invention of the shopping mall, there were (and still are!) vendors on the street in heavily populated downtown areas selling various types of fast food, hot dogs being the most immediately familiar. Shopping malls were, after all, modeled after downtown shopping districts.
Different cities have different characteristic street vendors. For instance, although the "dirty water" hot dog stand is the classic image of NYC, today a New York street vendor is just as likely to sell falafel. In Philadelphia, the vendors generally do an attempt at a cheesesteak; and in Germany, the vendor specializes in döner.
It's not uncommon to see someone open one of these in a large town or small city that really can't support it. Does your town have that one storefront that nobody ever seems to stay in for more than three years? This may be at play. Some shops may work fine in one place (like a chocolate shop in a city) but turn out to be far too narrowly focused when transplanted to a more sparsely populated area. If you can draw in customers from other towns, you may be able to stay afloat. And even if the area can support one such shop, if someone else inspired by your success tries to start up one of the same in a nearby town then there will likely be trouble for one or both of you. The same if you expand and find out the market isn't there for a second shop.
An unintentional example, related in Michael Binyon's book about ordinary people and life in the Soviet Union, Life in Russia, was of a local store that sold absolutely nothing but zinc buckets, due to the fact that they ordered stuff from the nearest factory and that's all said factory ever made in order to fulfil its quota.