Bitmain S2s are available for $1650 right now ($1.65 per GH), and they ship on 5-25. The S2 also comes with a power supply and doesn't require a host computer, so the pricing is basically identical except I have less hassle to setup and run a S2.
Even though that group buy is only for 100 units and is around 30% off bitmains price, $1.65/gh is really not even close to $1.35/gh.
Where are you getting $1.35/GH?
According to this link, the price is $1.50/GH plus the cost of a power supply and rpi, plus $200 shipping, which equals between $1500-1600 for 800 GH.
https://bitcointalk.org/index.php?topic=421921.msg6771994#msg6771994