.09$/kWh

Well I got good results with mine> but  a really finicky machine.

I could do 1400gh with 1200 watts  all day and all night long.

 but It :

 1)needed extra fan for cooling.
 2) would not underclock and hold the settings.   if I set it at lower freq it would start at 950 watts and 1100 gh and over night be 1050 watts and 1200gh

I did not feel I could travel away from it and leave it alone.  I do this with my s-3's and now with my sp20's

I go on short 2 day trips and the antminers and spondoolies hold onto the underclocks.

I turned mine back in for a small loss.

oh not to mention I had to close my garage door to warm the room to get it to start.  

then open the garage door to keep it cool enough to run.

A lot of work for me.  Plus the fear of burning.  I just could not do a proper setup with it.

Now on a side note these were lucky gear for me.  I really wanted sp20's but they were 1100 usd when this prisma came out.
 So I went cheap purchased the prisma and the sp20's dropped over 400 bucks in price.  
So I lost 50 bucks on this and saved 400 on the sp20  net 350usd gain.  I was lucky with the short tubes as well.