don't!
it's not profitable anymore IMHO.
gpu-s are expensive, high power consumption and scrypt asic-s are behind corner.
you'll never gonna make ROI.
if you think you'll gonna resell those gpu-s think again. shit load of them will be for sale everywhere after people stop mining with them! if you think people will made up some XY coin with XY algo to keep gpu-s in mining business think again.
my advice, keep away from gpu mining.
wait for next generation of miners (5-7TH) since there is no peace of asic gear worth of buying right now and be fast on buying.
Not true at all.
For 1000$ lets see what can you get. in USA R270 costs about 200$ for one, one can make about 400-420Kh/s
You need some normal PSU ( some 600w ) thats some 100$ ( well a good one not the cheap one ) to run 3xR270. Then you motherboard, cpu and memory some 150$.
So 600$ for 3xR270, 250$ for PSU and other stuff. You need extenders, then frame, and USB flash ( for Linux ) that shouldnt be mroe then 70$
So for less then 1000$ you get 1,200Kh/s thats more then 12,000kh/s with 10,000$ investment.
With that much hashrate he can make about 100LTC per month, if he mines alternate currency probably some 120-130LTC when he sells and buys them.
LTC price atm is kinda low, "only" 18$/ltc, but scrypt asic miners wont be delivered until Q2 ( some say not even in mid Q3 ). And also lets face it even if they are delivered there wont be many of them out there, so he still has some 3-4 months of mining. In that time he can make 300-500LTC ( lets say 400LTC ). If he sells them for 20$ he wont make much ( granted he will lose ), but if he waits and sell when the time is come ( and some say price will go to 50+ when reward get lowered ) he can make a lot.
Then he will still have hardware, you can't expect to sell for 100% of what you payed but even if he sells for 70% ( and he will ) thats 7000$ back.
Or he can buy 500LTC for that price and gable on that. This way he stands to lose 30% ( if he buts gpus to mine ), and to cover expanses by selling them, while he makes them...