your calculations are wrong.let me tell you why:
- you didn't add shipping fee witch is about 0.8 BTC
-you didnt add duty fee witch is about 15-25 %
-you didn't add electricity costs witch will cut to about half the profits you got on that calculator
- you only did a 10 % diff increase which is not possible (never was and never will be, despite the manufacturers keep telling us that this will happen).most probably will be 15% or more

After you take all these in consideration you can make a real calculation:


http://www.vnbitcoin.org/detailcalculation.php?name=Bitcoin_Mining_Rig&startdate=2014-09-26&costperunit=1800&wattperhour=1000&gigahazarate=2000&daytoincrease=12&testlopfirst=11&diffincrement=15&bitcoinperdollar=404.87&electriccostinput=.13&begindifflevel=34661425924

good luck getting a ROI with this !
wise thing to do : just buy 1.800 $ worth of bitcoin now !