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.