assuming that you have sufficient WTT tokens to cover the power usage (1500 watts + 10% = 1650 WTT needed).
At today's rates (which are pretty much guaranteed to change for the worse), the D3 would take over 1,000 days (2.77 years) to ROI, and the Alpha 200 would take ~265 days (ETH), ~450 days (ZEC), ~309 days (ETC) to ROI. Assuming that ETH is still planning to switch from POW (Proof of Work) to POS (Proof of Stake), but because we don't know when, maybe 260 days is OK, or maybe not.
You are correct, current mining earnings are too low comparing with miners' prices. But in the next few monthes situation may change a lot , with final mass adoption.