I may be wrong for some areas, but every vehicle I know that has decals / sponsors is from somebody they have already done a lot of business with or they own that business / good friend owns that business.
Usually at best the sponsor pays entry fee / some of the money asso. with cost at the track.
I have two people that have helped me out. I've spent $1,000's with both of them and at some point they wanted to "help" with parts or labor and I put their decals on my truck. However, I still pay for most of what I get from them. Nothing is free. In return I do send both of them business.

It's nearly imopossible to get $ from a supplier / sponsor if your not already winning. If your already winning you probably don't need or want their help anyway!

Bottom line is you have to already have money to get more money!
lol, but true.

A lot of the times paint sponsors do it for a good price or cost of materials for putting their logo on the car.

X2 And all you have to brush the wall and you get to start over.

yup....spend the money elsewhere....solid colors ,blue....white... hugger orange, something easy to fix up quick after a scrape or two....its gonna happen.