Need some help building a GPU mining rig for altcoins

[JBrace1990]

I'm currently looking into building my own mining rig and i could use some advice on parts, a case, etc. I've been doing some research into this, and my budget is somewhere around 5-7K.

The biggest issue I'm having is finding suitable parts that aren't highly marked up.


For parts, I've currently chose these:
CPU/Mobo: http://www.newegg.com/Product/ComboDealDetails.aspx?ItemList=Combo.1466003

Power Supply: http://www.newegg.com/Product/Product.aspx?Item=N82E16817494006

5x graphics cards (potentially 6): http://www.ebay.com/itm/Sapphire-AMD-Radeon-R9-290-4GB-GDDR5-2DVI-HDMI-DisplayPort-pci-e-Video-Card-w-/201003977849?pt=PCC_Video_TV_Cards&hash=item2eccc54c79

And using these risers: http://www.newegg.com/Product/Product.aspx?Item=9SIA2C50US9991

RAM: http://www.newegg.com/Product/Product.aspx?Item=N82E16820145218

Hard Drive: http://www.newegg.com/Product/Product.aspx?Item=N82E16822136771


I think it should be a pretty solid rig, costing about $3,700 and averaging 5,400ks/s.
Any suggestions on a case, or swapping out the parts? Maybe somewhere to get like 7990s cheaper instead of those cards? (they're the only real ones I could find).