A few years ago there was a place that tried renting out high end tactical rifle scopes, forget the name, evidently it didn't work out. All I've seen recently is some non-tactical hunting lower power stuff, and general optics like binoculars/spotting scopes.
Buy deals used and recover most of your $ is the best option if you like to play the try a bunch of scopes option, with low financial risk, as long as you have tons of freed up $ to get multiples at the same time to actually compare them. That said, I'm always a bit leary of things like optics used, especially if you don't get a transferrable warranty. The same used to be true of camera lenses before digital SLR bodies could adjust their sensor planes to the lens for max sharpness. Guys would buy 3-4 lenses, pick the best one and sell/return the rest. Buying used there's always the risk of getting someone else's lemon.