I'm stuck between ordering an ASIC miner (which nobody can get) or building a GPU mining rig. I have $4k to build one, but I won't order anything till I've done my homework. I don't want to order an ASIC miner, and have to wait a year to get it!
4k is a lot if you went with asic thats like 3 avalon rigs no idea what that puts out but if we use bfl as a guide its about 75ghash/s
a 7970 is getting me .5ghz so you need 150 of those to match the power, which is 37500watts of power just on gpu so you wouldnt get anywhere near that power, 4k might get you 5 1.5ghz rigs but it would be hugly inefficiant but, in contrast youd have your 8ghash by weeks end its your call