Alibris is one of the most customer-friendly sites I have shopped at.
I'm a regular customer for knitting and other needlework books, which can be quite expensive. They have great prices and effiucient service. I highly recommend them.
Non-existent customer service/tech support. Impossible to get a reply. Finally got through by phone after many, many tries, and was told that "the" tech support person wasn't there.