fantasy solution: mount a bunch of open faced stems on the wall, and just bolt and unbolt the ones you want.

more realistic elegant solution: set a pairs of large-diameter pegs in pairs vertically on two 2x4s that can support a dozen handlebars each pair. go from 2' off the ground to the ceiling, with a pair of pegs spaced to be able to easily reach a pair from the back without knocking off handlebars from the row above it.

hard reality: stop hoarding handlebars that are identical if you are not actively using them. keep one extra at most. if you haven't already, become the "bicycle fairy" to people in need. the only thing you win when you have the most toys is a low-grade organizational nightmare.