I came across a rather negative blog regarding two booksellers who sell on Amazon as third parties: PB Shop UK and Book Depository.  Let me just say that I have never had any problems with these two sellers, and between the two of them I have sourced probably 40-50 titles in Classics, Bible, or Ancient Near Eastern Languages.  They are slow, but pay attention to the shipping estimates listed, since they are usually shipping from the UK. I have generally gotten a better deal on T&T Clark, Oxford, and Harvard University Press than through any other seller.  I would give them both high marks,  For many years, I have been building a library on the Deuteronomistic History (Joshua-2 Kings) and those two sellers have contributed tremendously.