Hi Tyler,
I'm not sure what decals you are required to use;
But numbers, drivers name, and maybe a sponsor or two in vinyl will likely run about $80.00 and up. (check the rules to get the sizes right)
You could paint the numbers on if you have a steady hand or stenciles, and maybe save a few bucks that way.
If you have some art ability, that could be a major plus.
You will need to use contingency sponsor decals to receive any monies for using their products. I believe most will supply you with decals, or at least minimal cost.
Don't know if that is much help.
Steve