this has got me interested, how much electricity are you guys using?
prices are always going up, no idea for sure what the rate s at current, got to be 12p/hr at least, so 2kw of power would be 24p/hr, just over £5 a day.
so say i get 2 coins a day at around £17 a pop, then there is £29 profit a day, so a 2k setup would pay for itself in 3 months, then you sell up and get a bigger rig, virtually paying for the upgrades and syphon off a percentage as you go along.
the key as far as i understand would be to balance power against productivity, ASIC would be the way to go, but cost would be higher although energy usage would be lower.