you will make more with vga, at least you can get them now, and even with electricity cost, you can make profit in two month
example
4x7950(they need 250 watt each, so 1kw per hour) at 600mh=2400mh x24 hours=0.12 bitcoin a day=3.6 in one months
energy cost 0.25 x 24kw at day= 6 euro, in one month 180 euro
now 4,5 bitcoin are 105 euro x3.6=about 380 euro
so you make about 200 a month.
obv this at current exchange
good thing about vga, is that you need them anyway, so don't take in to account the total cost of 4 vga
+1 but Jalapeño nice small unit i would like to keep it on my desktop just for fun
and cheaper than GPU .