http://www.coinwarz.com/calculators/bitcoin-mining-calculator/?h=4860&p=1210&pc=0.05&pf=1.00&d=199312067531.24300000&r=25.00000000&er=548.56030000&hc=0.00
At the moment, an antminer S7 batch 1 would generate a little over 5.2 dollars/day, in about 2 months (after the halving), that would be 2.6 dollars/day (on average, the actual income could be a bit different, and would change over time).
I don't think it would be wise to buy new S7's (just my personal opninion), however, you might strike a deal with somebody that already has the hardware, and pays more than 5 cents/kwu, maybe split the difference and both make a little bit more coins