I already own some.
Some went up shortly after I bought them (Shadow of the Ninja and Shatterhand NES along with Kickmaster on the NES.
Now the one I want to own is Marvel Super Heroes Vs Street Fighter for my Sega Saturn, and Street Fighter Zero 3 for the Saturn. The first I have found some for under $50 for a change (been collecting for years, it's never been cheap, but would compliment my X-Men Vs Street Fighter Saturn copy nicely), in Zero 3's case it is $150, and I have a superior port on Alpha Anthology on the PS2, so no biggie.
Of course I just for the holidays boosted my collection by 8 more games off Ebay, puts me at 1,153, some of them pricey now, some I got lucky on and found for cheap. These games are by no means expensive, though the English Rival Schools is getting up there slowly, so I went the import route with it. The second game on PS1 is around $30, nothing too bad, but the PS1 price bubble hasn't really hit yet.
I've found game prices drop during the Christmas season, then rise again after. But sadly the inflation bubble shows no signs of popping soon, so long as there are greedy bastards out there looking to make money off a poor dumb chump.