Crossfire 2 HD 5750s or 1 5830

If you are going to be using an Eyefinity setup I highly recommend you pay slightly more for an HD5850;
http://www.newegg.com/Product/Product.aspx?Item=N82E16814127500
That is not only the cheapest one but it has one of the best coolers and allows you to control the core voltage for a huge overclock(35-40%)
FYI almost all of the poor reviews on newegg are from people complaining that it didn't work with past versions of MSI Afterburner and can be ignored.