While I like the concept, the prices are very high.  With a 1070 rig (I don't know the hashrate you are guaranteeing with those... I'll guesstimate 32Mh/s) it would take you a long time to pay off that rig.  Considering difficulty rises I'd say it would take you 24 months to break even.  You'd have to be gambling that ETH will go up in its worth quite a bit to make it worth it at these advertised prices.