If you purchased an S3 today and you had it ready to go, it would take 86 days to ROI when you include the power supply that you need to buy. When you factor in the electricity its even worse. Most of us who are still mining purchased when ROI was less than half that.

So you are a little late to the game. If you are smart about your money, you should just purchase BTC today and hold. Wait and see if the price goes up and keep reading the forum for advice on what to do with your Bitcoin. Most of the manufactures are going in the red if the price doesn't start to go up, or they come out with something like 0.20 per gh price on units. Right now your are seeing 0.76 to 0.63 per gh.

I have 30 machines from Bitmaintech and they all work great but I am making less than half of what I made 2 months ago. But my units are all paid off so I'm good.

Buy and hold, wait and see. READ the forum everyday!

Hope this helps.