Usually a remake, or re-release of game will drop the value on the originals, it did for a short time with Marvel Vs Capcom 2 (that's when I snuck in and paid cheaper for a copy on the PS2 than I had seen in years), Earthbound dropped for a short bit too, but then went back up. MvC 2 got delisted, it's value on PS2 went right back up. A game like Mizubaku Daibouken/Liquid Kids got re-released on Taito Legends and Memories on PS2, it's value on Saturn did not change at all, but then again, the Saturn port was Japan only to begin with (and arcade perfect as well).
Then again, I'm a collector, I sell nothing, and I do not smile down on resellers who artificially drive up the costs of games to where they don't have to get a real job, and make money off of poor saps on the internet, and price the real collectors out of the market. My passion to see these people walk onto a busy highway into traffic burns brightly.