Looking at that calculator, it looks like the most 7.5TH will produce starting March of 2014 is going to be about 65 Bitcoins. If you paid $12,800 for your equipment now, then you've invested about $196 per Bitcoin once you've mined all 65 of them. ($12,800 ÷ 65BTC =  $196.92)

Why not take your current $12,800 and just go out and buy 65 Bitcoins now and wait for the price of Bitcoins to go up? At least you have all your bitcoins right away and not have to wait until September of next year. You would probably turn over a profit faster this way once the price of Bitcoins does go up. (Which I'm sure it will!)

Just a thought.

I would love to hear anyone else's thoughts on this as I am having the same dilemma right now whether to buy ASIC equipment or just bitcoins for future gains.