Just to save folks a whole click or two, it's $750 which does seem ... steep but I'm not into retro computing (yet, a part of my brain feels like adding). I've heard it mentioned on Youtube ("8-bit guy", I think) but never looked it up, thanks GP.
Here's my 2 cents: no one needs that kind of stuff. Retro can be free, and only reason you would want to break out your wallet is if you really care that much about things beyond the game.