You could have PC-10s modded to play standard NES carts and put excess inventory in there for display. You could also try that with an AES or the SNES arcade thingy (forget the name). Heck, if you're good enough, you could mod other consoles to do the same thing! Pay-per-play because extra revenue streams are good.
It could be profitable to have an online storefront. I'm sure there are many DPers who would love to buy from your store but would be too far away from it (like me).
Maybe hook up a PC to some in-store speakers. Play SID and NSF tunes... create an atmosphere.
Best of luck!