Relative to a lot of hobbies, video game collecting is a bargain. With that said, many of the more expensive hobbies I'm thinking of would be out of my price range.
Video game collecting has become a lot more expensive overall since everyone is now aware that retro games are collectable. Back when I started, people priced them like they were giving them away and even at game stores, prices were very low for most titles. I hot a point several years ago with most retro games where I wouldn't pay what they're going for and luckily due to hunting for them on the cheap and being patient i was able to find many retro titles I wanted for pretty cheap.
The magic number I have in mind for a limit on price for a single game is $200, but depending on how badly I wanted the game, how good of a deal it was, and also how much extra money I had at the time, I may go higher. I can think of two games tha I'd actually do this with, but both would have to be a screamin deal still.