I was mainly reacting to seeing Syd Mead's Terraforming for $1000, and Air Zonk for $650. The Genesis inflation is surprising, but I think you're projection s will be right.
..Speaking to a friend who is a Video Game programmer, I brought this topic up, and he credited the tangibility of retrogames, and how everything now is completely online. Looking at MMO environment games or iPhone games, hey cited the interface aspect of current games and apps: that once the servers go offline the game doesn't exist anymore. If you have a turbo or a Genesis, you own the game, and thus, you can play it "off the grid". He's unsurprised.
Apparently its hip to own a copy of Sonic The Hedgehog.