Right now, I spend next to nothing. I am lucky enough to have people ask me to ride their horses and show them. I also do some basic training work and have many friends with horses. I pay for my own equipment of course, such as my helmet, and I pay for clinics and lessons. Overall I'd say I spend $300-$500 per year
(and that's a generous estimate, including horse show food
All this should be changing fairly soon though, since I might be taking on a mare...