Smart BitCoin Miner, is it worth it?

I've been thinking about starting a bitcoin mining business..

I saw this Smart Miner, does around 20TH/s, almost 5000$ but according to somemath, it might pay for itself in less than 6 months.

At 20TH/s i can get this:

This difficulty:72722780642.5
Dollarsper Day -0.13830783 BTC -$43.97
per Week -0.96815484 BTC -$307.78
per Month -4.20974472 BTC -$1338.28 :money:
this diff (est) -1.60177761 BTC -$509.21

Of course these values are changing all the time, but never seen them bellow $1000/month..and of course, there's the electric bill, all things to consider, but i wouldn't mind hearing some experts about this
Anyone here with some experience with this? I want to mine for myself, will think of a btcfaucet websitelater.