With that said I challenge anyone to show me a scenario where an SP31 is the best option.
From where can you buy AM Tube at that price?
I mixed up the power consumption, it should be 1.09 w/gh not 1w/gh when overclocked. It's fixed now and the tube is still the most profitable. It's ~$1700 more profitable than the sp31 in half the amount of time.
Each tube is ~0.96 btc each and can be overclocked to 920 gh/s at 1000W. A modded server PSU is ~$25 per miner.