you can calculate it yourself... all BFL equipment use 5 watt per gh/s. and you can use a bitcoin calculator to see how far you get with 30gh/s. Now it's a whole different story with the current BFL miners. $ 2500 for 50 gh/s and producs are not shipped yet.

I estimated difficulty would go up between 70m and 78m, but got 65m. Next difficulty will be between 75 and 85, "thanks" to these ASIC miners (mostly from BFL)