I think it highly depends on how well you choose the bounties you participate in. They usually pay percentage of their ICO, so the more successful project you choose, the more you earn. The rewards can thus vary widely, probably somewhere between $100 - $10k per let's say 3-months running bounty campaign.
I think it's up to you to choose what good ICO or to follow. And Usually, they also pay a percentage of their ICO.
So the more projects you choose and the more you get. I hope someday you can get it