I try not to attach rewards to things my son finds intrinsically motivating. My son is overly motivated by grades, and I do pay for A's (on days he doesn't yell at me). But he has a lot of temper tantrums so I haven't paid for an A in months. He has one daily chore but if he does more I'll pay for those "money chores". It's fine for motivation, but honestly, he doesn't actually earn money this way. IDK.