Digestive upsets can usually be dealt with entirely with foods and proper preparation. Since I'm not sure which digestive upsets you're dealing wtih, I'm not sure what to offer up as options! :) Triphala is certainly a fantastic option and should do you lots of good. :)
When money is an issue, it's even more important to heal with just food, isn't it? :) so please check out the recipe for Kichadi, it's a wonderful complete food that is excellent for digestion. My Bowel Management notes has lots of suggestions for constipation, and Power of Digestion deals with everything else. (see FAQ)