Is that serious? How do you get those cheap prices? If I build up a rig with say 3 x 280x gpus that have around 3 x 710 KHash/s = 2130 KHash/s I have to pay at least:

100$ Motherboard
3x 500$ 280X GPU
25$ Ram
3 x 30$ Riser Cables
230$ 1000 Watt PSU
----------
Total: 1945 $

 That would effectively be 1945/2130 $/(KHash/s) =  0.9131 $ /(KHash/s). The power consumption of this rig with 3x 280x would be 3*250 W + 100W = 850W (GPUS + Mobo). I live in germany and have to pay at least 25 $/KWh that would mean i would have to pay for this rigs electricity 0.25*0.85*24*31$ = 126.48 $ per month. Effectively this would be a total of 126.48/2130 $/(KHash/s) =0.05938 $/(KHash/s) per month which is nearly double the electricity cost of 0.04$ which you charge.
This would mean for my rig I would have to pay a total of 0.9131 + 12* 0.059 = 1.6211 $/(Khash/s) for one year mining. Compared to your contract that effectively costs 0.99+ 12* 0.04 = 1.47 $/(KHash/s) for one year mining! This is much cheaper plus I don't have to maintain the rig and worry about cooling and noise!

Are my number wrong or is that a pretty damn good offer?

Greetings,
b0n1