You have to be careful. Drugs manufactured outside of the US may or may not have as good controls as from our FDA oversight. That said, there are quite a few reputable online pharmacies sourcing meds from India, Mexico etc. It is big business and they are careful to maintain their reputation. You are theoretically receiving the same drugs that you would get on the shelves in those respective countries. I still don't understand what the laws are concerning importing non-controlled drugs for personal use.
Buying vet meds or chemical grade drugs like the pond treatment is controversial as well. I don't want to weigh in on that because it is the only way some people are able to get treatment. The chemical grade stuff I would be most concerned about. Funny thing is as far as I can tell, there are no laws against you buying these.