I just picked up a copy at GameStop on Tuesday for $25 so I can clean up the rest of the achievements.
Granted, it was the last copy they had.
Also, apparently the game only sold around 300,000 copies when it was out, so there aren't as huge a number to come by as some other, more popular titles. Supply and demand generally dictate price...
Oh, I used to be disgusted but now I try to be amused.