I do like this idea but sadly every system like this is open to manipulation to some extent. It would be difficult to verify the quality of someone's ratings / reviews. The idea is most definitely something worth exploring though - especially the badges idea.
GameJolt have an XP type system where you "level up" when you have enough, earned by various actions. Badges for specific things like "entered 5 game jams", "released 10 games", "rated 5 games" or something like that would be better to me. I'm just not quite sure about earning actual $ to spend in store though - I guess a lot depends on where these $ come from. Itch itself? A fund donated to by devs perhaps (a donation to make their games eligible to buy in this fashion perhaps?).