Question about Hydro Thunder on N64...

Hey guys. I've been meaning to ask this question for a long time but I don't feel like I've gotten a complete answer out of it, but... is there any reason as to why Hydro Thunder on Nintendo 64 is so expensive?

Okay, I know a few things beforehand. Yes, I'm aware that there are two cartridge variants: One that is a blue cart, the more common one, and one that is grey, the more rare variant. But other than the cartridge color difference, I can't see why this game is any more rare or high-priced than it should be.

Was there a bug in the initial release that the developers had to patch? Is there any difference at all to the two cartridge variants? Is it still worth picking up even if I can only find the more common version? If anyone can tell me the answers, It'd help me a lot. I used to play this game in the arcade all the time and I feel that it'd be nice to play with my friends on my N64. Thanks guys!