No allowance, they get free room and board what else is needed?
They want money get a job.

This.
Putting a monetary value on chores or good grades sends the message that kids have to receive money for doing things that they should just do because it's the right thing to do. Everyone contributes for the good of the family, you or your wife would not get paid for doing the dishes, why should the kiddo? Schools aren't paying kids for grades, why should you? Advancing to the next level, self enrichment, independence and ultimately successful employment is the reward for good grades, not a few extra bucks when report cards come out. If the little urchins want something, it's up to them to show the initiative to earn some money on their own doing the jobs kids can do.
Not that there's anything wrong with treating them when it's deserved. The most effective, and long lasting reward systems work when they aren't expected. For example, "Surprise, you're getting a puppy because you've been keeping your room clean, doing good in school and haven't inflicted bodily harm on your siblings." In other words we are rewarding you for being a decent human being, but if you want regular money in your pocket get a job.