That is your opinion, if you find it cheaper elsewhere please go ahead and buy it else where. When we bought them we got them for $4500 each, so be happy that you are getting them for around $1800 or $1600 each if they buy the lot.
Actually you paid ~10 BTC and you want 8 BTC after more than 6-7 months of usage.
Your calculation takes into account when USD rate was 475, so your argument is void. At current rate our purchase price would be 21 BTC, so 7 BTC is not a bad deal.
We would consider 6.5 BTC if you continue hosting with our hosting provider which is cheap and charges a low $75 /KW/Month.
Wissam