You sound like you know what it will take to make it work.
As far as a build guide goes, I would buy used all the way. You can get the Asrock H81 PRO BTC on Ebay with a low processor for $60-70. A R9 280x goes for only around $170 too. Used power supplies aren't quite as plentiful but I've seen some EVGA 1300w go in the $160 range.
Now back to fighting
8/6/2014
XDQ, 110@ .00046 = .05047350
BLC, 400@ .00001402 = .00559398
ELT, 920@ .000005 = .00458850
UMO, 40@ .0001 = .004
Total .06465598 Btc * $590 = $38.15 Usd
This was from 23 GPUs, mostly 270s. When the cards themselves are only worth $100 or less, getting more then a dollar per card (yes even after power) is well worth it to me. This was set-n-forget, not necessarily the most profitable.