If you are really serious about obtaining a sponsor get a professional to write you a generic proposal and start selling yourself like crazy. I'm sure there are a lot of small local business's that would sponsor a disc golf player as long as they were getting their money's worth in advertisement. I was in the process of this right before I broke my leg a few months back. It will take a lot of leg work.
999 "NO's" may be worth the suffering for the 1 "MAYBE"