Instead of brushing your horses tail every day, braid it! And then, to protect it, put a tailbag over it.
You can make those oh so expensive tail bags by... taking a worn out shirt, or jeans, cutting them off, sewing one end shut and cutting little ties on the other end. Ta-da, works just as well, and you're not so worried about losing the $50 one you just bought.
Instead of buying new sawdust for your trailer, use old (not dusty) hay. Lots cheaper than sawdust.
Buy those expensive showshirts at bargain stores... or just find a shirt that has potential and add bling to it.
Share shirts and show clothes, along with horse blankets, halters and other show equipment with other people in your barn/club. Awesome and cheap!
Hmm... I thinks I have more, but I can't remember... lol, you guys have any?