Incentives

What are your thoughts on incentive programs in the classroom?  My theory is basically this... whatever works!  Although in an ideal world, every child would be intrinsically motivated to learn every subject with ease, this is not the case in my classroom.  Every child is different, I value and honour that, so therefore created different incentive programs for every learner.  Some children in my class need daily reminders to choose some work in different areas of curriculum. Since I know these boys would rather talk about their recent Mario Bros accomplishments than do Math, Science,  Language or anything else that has to do with learning- each time they complete some challenging work they recieve a coin.  If they can collect 12 coins in a week they recieve $1 to spend at our classroom store.  This money can also be spent on purchasing a party for the classroom.  Part of me feels guilty for bribbing these children to learn and the other half of me thinks- how guilty would I feel if I couldnt get them to do any work.?  What do you think....