BFL Single then order an ASIC Upgrade. Right now the BFL Single gets about 832 MH/s. I have 2. Both together earn 0.23 BTC a day and with ASIC miners coming on line that will diminished quickly.
How to figure how much MH/s it takes to earn 1 BTC :
http://bitcoinsbs.wordpress.com/2013/01/16/how-much-mhash-does-it-take-to-mine-1-btc/I have been running both since late October. I have earned about 32.5 BTC. I'll be sending them back the end of next month in order to receive two of my three ASIC miners. It was worth it to do that back then, but with the ASIC coming online, you might not even cover the shipping costs each way.