You'll lose more money with down time - trying to get this shit work 24/7 (night time is a huge issue here) - than you would by paying for electricity.
Watching... Here's my situation: at night, my electricity is 10 cents a KWh. During the day, it varies between 15 and 30 cents. If I could cut the day shifts or even redistribute the load, I could save quite a bit. But $900 for just 37Gh sounds prohibitively expensive.