I've recently decided to start trying to get boxes and manuals for all my old PC games, and build period-accurate PCs to play them.
Some of it is CRAZY, but for the most part it's a lot better than the console gaming scene.
I just bought like $100~ of boxed PC games from 1992-1998, enough to fill a 4x6x4 foot box to the brim.
I got Monkey Island 1 2 and 3, King's Quest 2-4, Shogo, a bunch of old sierra titles, and like 8 3DFX compatible old 3D games. It's fantastic!
You see some scalpers though, like one guy was trying to sell Conquest of the Longbow for $60 on 5.25" floppies which probably don't even work anymore.
Anyways, the retro fad will die down eventually I hope.
I haven't been into cartridge based Neo Geo stuff for long, but it's a little expensive. Luckily, I have a NGCD that at least lets me play some of the expensive games cheaper.