Even with cheap power you will never have a positive ROI with them. Your only chance would be if the value of BTC increased significantly or the difficulty plummets.
Call me crazy, but i feel lucky i might get something delivered at last.
According to BA the X-1.5 runs 160 GH/S on 100W. If that's true i'll be looking at them for at least a couple of months (i don't have very expensive electricity).
If you paid for the miners in BTC then ROI won't happen. You'll never mine back the amount of BTC you used to purchase them.