I've bought about 16 drives from goharddrive (through eBay). Most of them 5+ years ago without any failures. So I can't say how well they honor their warranty, but they have been around for some time so that is probably a good sign.
If you are running your power supply near its limit I have seen that cause drive drops as well. If you continue to see drives drop that seem to be functional and cables/HBA don't seem to be the cause, you might want to swap/upgrade power supplies if you can.