Best possible 3 - 4 rig setup?

Ok guys so I am looking for the best possible setup I can in regards to cost and power. I pay nearly 28 cents a Kwh so it needs to be pretty good xD
The cost for GPU's here are:
270 = $220
270x = $240
280x = $380
290 = $530
290x = $630

What do you reccon would be best? Also will all four rigs work in 1 house? Also how loud will it be (Can I hear it through a door loud or? How much would it be $/Kh and Watt/Kh? I don't mind price at this point in time although lower is of course better. (I will try get a portable air conditioner in as well) And how much would all this cost per day in power? (I will be using multipools for most profit)
And finally if I was running a 12000 BTU Portable A/C would I need any other fans pushing air off the cards or would the cards fans work fine?