You are right, I did miscalculate my power costs.

700 W for 2 antminers (measured using KillOwatt meter),  24 hours a day, that's 16800 W or 16.8 KW.

At $ 0.10 / KW, that's $1.68/day * 180 days = $302.8 for half a year.

Subtract that from the profit, and that knocks it down to roughly 11% profit.

Still, profit is profit. You're not getting 11% by investing in treasury bills, and AntMiners are way safer than the stock market (Nothing exciting happens in my basement, heh).

Those Antminers are still running, and will be profitable until roughly October/2014.

Thank you for pointing that out.