There's no free lunch. Or pass through a river. Or, in fact, a bit of knowledge. We all know that. Methods of paying for these useful things, however, may vary.
The Fair Folk, however, has an interesting tendency to only accept payments made in actual valuables. That is, things you'd be reluctant to part with. Things with emotional value, if little material weight, or things that are part of you (not necessarily arms and/or legs, but, say, the hearing in your left ear or your first childhood memory). Or favours that will be pain to pay, sometime in the future.
This carries a significant risk of being plot-fuelling, as well as emotionally engaging for the reader (do you feel sad for a guy who has to pay a copper coin to pass a bridge? How about one who must give up "whatever they find at home that they were not expecting"?)
The Bazaar of the Bizarre often will take these, and so can a troll or another Threshold Guardian who isn't interested in Secret Test of Character. Deals with the Devil are also likely to involve these as the price that the dealer must pay, and are more likely to screw you over down the road. Compare Insubstantial Ingredients.
- In one Doraemon story, Nobita comes across one of Doraemon's abandoned gadgets. It talks to Nobita and introduces itself as "The Devil Card". Its demonic projection tells Nobita that he can shake the card and get virtually limitless amounts of money, but in exchange, his height will be reduced by 1 cm per 100,000 yen he pulled out of the card when the midnight (i.e 12:00 AM) comes. This causes a problem later in the story when his parents found the card and uses it to gain a lot of money without knowing its consequences for Nobita. He later resolves this by Doraemon using his "Grow-up Flashlight" on Nobita when the next 12:00 AM comes.
- Enchantress from Marvel Comics' Secret Wars is beseeched by Volcana to be teleported to Molecule Man's side, after learning that he'd been hurt by the X-Men. Volcana offers "anything" as payment, which Enchantress accepts. Later, when Enchantress needs to warn Asgard about a new and awesome threat, she cashes in Volcana's IOU by extracting Volcana's life energy for a huge trans-galactic teleport.
- Ursula the Sea Witch offers The Little Mermaid the chance to become human, walk on land and meet her dashing prince. Her price: Ariel's voice. "No talking, no singing, zip."
- Though in the Hans Christian Anderson tale the Sea Witch's price was a bit more tangible, her tongue.
- In The Black Cauldron a trio of witches trade the secret of how to destroy the titular artifact for Taran's magic sword. Later, they offer the sword back in exchange for the Cauldron itself, but Taran instead demands the life of his friend, Gurgi, and the witches oblige.
- Neverwhere: The London Below has a barter-based economy, but the Marquis de Carabas deals in favours, and Lamia wants to be paid in Richard's life.
- In another Neil Gaiman Fairy Tale example, Stardust has the slave girl discuss various exotic payments, only to settle for Dunstan's kiss.
- In The Last Wish Duny (cursed human) asks this sort of payment from Pavetta's father (in hopes it'll turn out to cure his curse).
- Jonathan Strange & Mr Norrell has Mr. Norrell's make a deal with one of The Fair Folk to bring a politician's fiancee back to life in exchange for a portion of said life and one of her little fingers.
- In The Gates of Night the party gets a night in an inn in Thelanis, the Faerie Court, in exchange for Daine's voice, though the innkeeper agrees to return a voice to him when they leave, like it was just a loan.
- In Wielding a Red Sword by Piers Anthony, Mother Nature takes the protagonist's stammer as payment for a favor.
- An exchange based on this trope is a major plot point in Ursula Vernon's novel The Seventh Bride. An evil sorcerer has figured out that he can use his powers to make marriage work as a Magically Binding Contract. So he flatters or coerces various women into marrying him, whereupon he "gives" them his name, and in exchange they owe him a "gift" of his choosing. So far, he has taken his previous wives' life, death, magic, will, sight, and voice, and plans to take the titular bride's youth.
- Shadow Police: Members of London's magical community often trade in intangibles. In The Severed Streets, Ross exchanges her capacity to ever feel happiness for being allowed to study the auction's ledger for 15 minutes.
- The Dresden Files:
- In Grave Peril, Harry's Fairy Godmother accepts a year of his girlfriend's memories in trade for letting Harry off the hook for breaking a magical vow. Unusually, she's able to recover the lost memories later.
- A variant in Ghost Story has same said fairy godmother so interested in the story of Harry's escape from his Evil Mentor and subsequent confrontation with an Eldritch Abomination that she offers information in exchange for Harry telling her what happened. (The Fair Folk being what they are, this is treated as a transaction.)
- Padraig, a Fair Folk in Pact at one point offers Maggie Holt his aid in exchange for his choice of something from her backpack. Thinking there was nothing of value there, she agrees. Then he uses an essay there to take her name causing her entire power and being to slowly unravel, while he impersonates her.
- The Kingkiller Chronicle has Auri a homeless crazed waif, who gives and receives a variety of gifts, some tangible and others less so, like a secret, a song, or a moonbeam.
- The Coldfire Trilogy has deals with the devil as a major theme. While sanity and free will are common tolls levied in exchange for power, the charges can get exotic - identity, memory and moral certainty are traded away too. At one point a character is resurrected in exchange for one of their personality traits.
- In Moonflowers, Chinese-American Ned Song makes a Blood Oath with his father's patron-spirit the Lady of Scales, since he needs to break The Wild Hunt's curse on his family. The Lady goes through memories and the color of his hair before they settle on the color of his eyes, and she notes that there's some risk of going blind—but some people gain powers instead.
- In order for the Dark Curse to be cast in Once Upon a Time, the caster must destroy the thing they love most, normally a loved one.
- On Lost Girl, Dyson gives up his love for Bo to a Norn to be able to help Bo fight her mother. He was expecting to lose his ability to turn into a wolf, which is what the Norn asked for the previous time he'd come to her for help. Kenzi gets his love back by threatening to take a chainsaw to the Norn's sacred tree.
- Changeling: The Lost: Goblin Markets accept such items as eye colors, springtime afternoon or a song. Justified in that they can be quite useful as Insubstantial Ingredients in the creation of magical Hedgespun items.
- Warhammer 40,000: Dark Eldar can directly manipulate souls, so it's often a price for their intervention. Sometimes they take other things, like heartbeats or dying breaths.
- In Welcome to Night Vale the pawn shop sometimes pays in cash and sometimes in intangibles like "a good night's sleep" or "an interesting idea about time".
- SCP Foundation
- SCP-738 ("The Devil's Deal") is a writing desk that offers a Deal with the Devil for various prices, like the death of your best friend or memories of your mother.
- SCP-1323 ("A County Fair") . The inhabitants of SCP-1323 sell fair tickets for varying prices: a joyful laugh and a sorrowful tear (1 ticket), a cherished memory (5 tickets), A Year and a Day (10 tickets), a lost love (25 tickets), and a favor (100 tickets).
- SCP-1879 ("Indoor Salesman"). SCP-1879 is a man who appears inside a person's house and tries to sell them something. The price he asks in return is sometimes intangible, such as "12 years of your time". When the person agreed, they disappeared for 12 years. When they reappeared they were the same as when they vanished, with no memory of the intervening time.
- SCP-2523 ("Goblin Market") . The workers in SCP-2523 sell anomalous Halloween items in exchange for such things as "The memory of a childhood family trip", "The ability to sing" and "Empathy".
- SCP-2791 ("Fauste Bank plc"). The entities involved in SCP-2791 sometimes demand non-tangible things as part of their Deal with the Devil, such as the memories of the summoner's name or a period of torment after death.
- In the Metamor City story "Whispers in the Wood" Abbie Preston trades a song to a greater Fae in exchange for the answers to three questions, and only afterwards realizes that the price included her memory of the song as well.
- In Adventure Time, Marceline's childhood stuffed toy Hambo is used as a component to power a portal for Simon Petrikov to reach Betty Grof.
- On Gargoyles The Weird Sisters oversaw a covenant between Macbeth and Demona. He would give his youth in return for her being able to fight for him. Both would share the other's pain as a side effect, and each would have Complete Immortality until slayer by the other.
- One Rick and Morty episode involved a shop run by the devil. Everything was free in terms of money, but each item came with an unadvertised curse. For example, one artifact increased libido at the price of impotence. Out of spite, Rick set up a shop across the street that reversed these negative side effects for a trivial amount of money.
- In Family Guy, when Brian and Stewie try to rent a helicopter, the shop accepts cash, check or a "jaunty tune". Now guess with what they pay.