Dave, below is a link to the flyer for this weekend at Tulsa. (I know that is too far for you) the entry fees are listed, as well as prize money minus contigencies. If I won one I would collect about the same money either place. Depends, of course, on what you products you have.
http://www.tulsaracewaypark.com/flie...20Pro%20AM.htm
You also have two shots at winning one each weekend. Saturday and Sunday are two seperate races.