Foa a mac , the fastest 27" imac and then have OWC do a turn key hot rod job for you (http://eshop.macsales.com/shop/turnkey/iMac
So start here: http://store.apple.com/us/configure/MC814LL/A?
(3.4GHz Quad-Core Intel Core i7) imac with standard amounts of RAM and a 2TB hard disk drive
And then have OWC add two internal 480GB 6G SSD drives ( you could make one a 250Gb drive as your boot drive) and swap out the 4GB RAM that comes with your machine for 32GB ( or 24 or 16GB) RAM, plus their three year warranty: $1798.00
That gets you up to $4147.00 ( plus tax and shipping)
I have a 2009 2.66 Ghz i5 quad core iMac with 16GB RAM (OWC) and just installed OWC's 3G 240GB Mercury Electra SSD to be my boot drive and it is way fast, For standard high resolution files Canon 21-22Np and Nikon 24.5 and 26Mp D800 files it flies. For the very high resolution pans (up to 12GB with layers) it is a bit slower but still awfully fast.