Keep Circulating the Tapes: The pre-New 52 Jaime run of the comic. The bound volumes are out of print, and Amazon only has a handful of copies of each volume, with the exception of the first—for that one you're at the mercy of resellers, and used copies are a minimum of $37. There are always the digital copies sold at Comixology, but $1.99 per issue adds up fast.
What Could Have Been: Ted Kord was originally going to be a prominent recurring character in Arrow, but the higher-ups stopped it due to having "other plans". Ray Palmer eventually took his place, but his character and background still heavily derives from Ted.