Since my build will require a lot of PCI slots the best thing to do is create a backplane, an expansion for expansion slots.
Instead of putting the GFX cards directly on the board I was going to put them on the backplane board(whatever you call it) to save room or the other way around it doesn't matter.
I've looked at gen 2 expansion boards and they can get pretty pricey but there's also other workarounds as well, I have hard of basically connection 2 PCs together but don't want to go that route.
Budget: $2000 with case.
Something like this but for PCI gen 2 X16 would be great, I have seen them for sale so I know there out there. Its when you want to find something you can't and you stumble upon it when your not even trying to look for it><