Yet by purchasing slaves you are increasing demand for slaves, which prompts the slave industry to acquire more. This doesn't strike me as morally pragmatic, it strikes me as wrong. The slaves did not volunteer for their duty, it was not their choice to leave their savagery, I see no way to argue that as being right. The best way to be the positive drop in the bucket is first and foremost to take the money out of the industry: don't buy slaves.
Moral pragmatism is coming in to possession of the slaves second hand (i.e. saving them from death), treating them well and releasing them and ideally giving them a paying job (given that released slaves in the US would likely have a rough go). Given the laws and social conditions, releasing them may actually have caused them greater harm, I can see having to make a less than ideal choice on this one for the greater good.
The harder choice is one more like what we face today (H1B) and more like what might be driving the cheating in India. These people choose their indentured servitude here, and you can't argue it's a step up, yet is entirely destructive and unfair. What we should be doing is giving them green cards. That will take the money out of the system and cut much of the cheating. The rest I would argue should be handled through testing that is more standardized and much harder to cheat on (with real legal penalties). Universities ultimately are not about qualifying people for a job, they're about education, it's on the student to use his time there productively. They should not also be the gatekeepers of qualification.