why do you want S7 for 900USD if you can get it for 720USD brand new with warranty?
(except you are looking for pre B8 miners)
people should just stop quoting the 720 number because you have to pay shipping PLUS customs in many countries.
So, at the minimum it is ~$770 in US IF you don't have extra from UPS (could be $20).
Judging from the obvious ESL situation, shipping from US would be like $100 minimum or even more, so $900 price makes sense.