How much do sponsers pay to put their logo on a NASCAR?

It depends on several things. The most important is the driver: the more he wins, the higher the price he or she can demand to sponsor the car. And the more popular a driver is, the higher the price demanded. Then there are full-season and part-season deals, "hood sponsorship" and "associate sponsorship" deals, whether the driver is going to star in commercials or just have the company's logo on the car (and where)...sponsor management is complex enough that the big racing shops have large staffs who serve the needs of their sponsors.