The price is very attractive but also very suspicious. I checked the 28nm chip prices from bitmine, 40 chips itself = $2800 ~ $3500. If you sell your whole rig for $3250, I could see no profit or a loss even though you copy the design from others and spent $0 on the R&D. There must be some hidden secretes here. Caution: focusing on fact, not the promises.
From what I have gathered these miners have chips which they have acquired from the manufacturer that made the bitmine chips directly, not from bitmine.
That is why you see so many Chinese 1TH miners before Bitmine released theirs.
Simply put, the Chinese are better businessmen.
That being said, if you are planning on ordering do use escrow.
The seller is fine with that.