Is this happening?
I don't have too many more PS2 games to get, but there are a few I held off last year and now they're double, if not triple what I remembered. Like, when did Dual Hearts become a $40 game? Last I checked it was like $15 on average. When Did Jade Cocoon 2 become a $25 game? It used to be like $5 - $8.
You might not see a full-on spike occuring, but I've noticed across many platforms lately not just PS2, there seems to be a scalping trend going on with obscure titles. Not really rare games, but games that are overlooked / obscure and look solid, are becoming the target of scalping. Doesn't seem to require any sort of demand for them, they're just sort picked at random - "this is worth a lot because most people haven't ever heard of it", I guess.
Gah, you can't escape this sort of thing with any platform nowadays. Seems like folks will pay about anything for a game, if it was $5 yesterday they'd buy it and if it's $50 the day after, they'd still buy it. At such a rate it'll always be a seller's market.