I still can't figure out why someone would pay $800+ for an S7 on eBay when you can get a brand new one from Bitmain for less. When I ordered mine, it took less than a week to arrive here in the U.S. No problems with customs, etc. Very smooth and easy. You could probably do pretty well buying a bunch from Bitmain and turning them around on eBay.
availability is why they buy from ebay. if bitmain took CC I think they would sell a lot more. Not everyone buying from them has BTC to spare or on hand at all if they a newbie and a wire transfer is hit and miss sometimes.
plus you can only find batch 7s on ebay/amazon/here which I would rather have over a new batch 12.