Well, you can do some calculation. The Antminer S1's power efficiency is given as:

We can determine that with 3TH, you'd be using 6kW. Let's type this into CoinWars (this is a link to a URL shortener info page, so you can verify I'm not dumping you onto a malware site). We're using Coinbase exchange values. This brings in $44.56/day at the current difficulty.

Assuming diff. doesn't skyrocket, and the price doesn't drop, you're looking at eventual profitability according to BitcoinX