On a smaller scale, you could simply ask local companies to sponsor you. Local horse-related companies are always a plus.
A friend of mine (Jane) had a friend in Real Estate who specialized in Equine Properties. The company helped Jane out financially and gave her a bunch of banners/shirts/etc with the company logo/info. When Jane went to horse shows, she plastered the company info on her trailer, stall, saddle pads, jackets, etc. She chatted around at lunch time to see if anyone was looking to buy/sell Horse Real Estate and handed out business cards for her friend.
I don't think they paid her a lot, but ya know, every little bit helps!