Aloe vera juice and slippery elm bark -- I did that with my OT Standardbred and he improved greatly. Prior to that, he was losing weight and generally didn't look good. We figured he probably had ulcers, but I didn't want to spend the $, like you, and preferred to try the other methods first. I bought both at a local health food store -- the aloe vera juice or gel in a one gallon bottle and teh slippery elm bark in bulk plastic containers -- about 3 cups worth at a time. Total cost was about $20 - $30 a month if I recall correctly.
The vet was much impressed with the horse's improvement in just two weeks!
I'd had to look up the quantities I gave him. I did write it down on an old thread here somewhere, but by gum, it was a loooong time ago! Does anyone else know off the top of their heads? If not, post back and I will look it up.