Home server with two discrete graphics cards

[chrislbaird 0]

I saw this video 

I want to do something similar with server hardware.  I know it may not be the best solution cost wise but I thought it would not heard to just research the issue. 

 

I am looking to build a server  with the following 

 

1.  4 x 4+ core cpu with hyperthreading 

2.  128 GB+ of ram

3.   2 PCI E x16 slots that support 2 nvidia 970 GTX

 

 

I want to run two different virtual machines with gpu passthrough.  I was thinking of buying a server  used off of ebay and upgrading where needed. My thoughts were first to look into the hp proliant side of things with a HP Proliant DL580 G7.  As I know very little about servers and server hardware I though I would post here for help. My budget for the server is around $1500.