Uh, maybe if that 0.0089BTC per GH (!) is for two years?... in one year you should expect to net about $5 from it.
ed: Oh, I see... it's 5 years. OK, then it's about break even... you'd earn next to nothing in years 2-5, but it should be enough to cover the initial cost...
well, not really, because of inflation and better investment opportunities
not to mention the huge leap involved in assuming this place will be around for 5 years
ed2: if it was more profitable to use it then to sell it to chumps, that's what they would do. just sayin.
using
http://bitcoinwisdom.com/bitcoin/calculatorDiff increase +20%/increase
Pool fee 0%
Power usage 0
GHs price 0.0089
That gives you a ROI @ about end of this year.
It looks like next diff change is going to be ~10% so that helps shortening the ROI a little bit
your difficulty adjustments are way off. +20%? over what? a month?
if you look at the last 6 months, the average is more like 60%.
that gives you a little over $1 in 12 months (*or more like $3, it'd be $1 if you started next month)
i was being generous with the difficulty level earlier. i guess we can be generous again and say that the current difficulty still has 2 more weeks. you'll make $1.25. after that, you'll make 0.9375, then 0.70, then 0.53, 0.395, 0.296, 0.22, 0.167, 0.125, 0.093, 0.07, 0.053, 0.04, etc. So, no, you never make your money back.
and even if you did just barely manage it, you'd be better off investing in something else.
(& just looked at first 8 days of current diff level, looks like a 20-25% hike to me)