Yea, the board design would be better I think than the code.
The gap between $25 and $150 is a bit large. See if you can come up with 3 more things for the $50, $75, and $100.
Remember you aren't trying to make any money on the rewards, its with the left over DiveDuinos that you sell that you'd make any money on. Your rewards are usually just break-even things.