Sad but not a single one of these machines will give you ROI. They will all become useless bricks as a few months after you buy your 1TH miner, theres a 2TH and when you buy 2 theres 3.
I've been mining for 6 months and made about $50 worth of bitcoin with ASICMiner Blockerrupters which are now more or less worthless and cost me £150 when new. Then I got a litecoin mining rig and was earning £25 a day back in November... flash forward only 2 months and I'm earning about £9 with a £1500 mining rig, the only benefit of which is that I'll be able to play games on it when it stops being profitable.
The difficulty and the number of miners joining the networks is making it impossible for anyone but the bigboys to play this game. If you sink just a few grand into this, you will have lost it in a few months. It's an all or nothing game now. You either hit it with a big hash-rate, or you throw your money away.
.As soon as scrypt mining ASICs come out, all of us with big powerful graphics card mining rigs will be screwed. The best we can hope for is to mine the most profitable altcoin de jour (which changes probably every 10 mintues) and convert that to BTC. There are many profit switching pools that will do that automatically and some will even convert and pay you in BTC.