My friend with a furniture business has a huge CNC machine and he said he could make my plates on his machine. For the trouble of setting up the machine to cut once, I might as well have him make 2 sets of plates.
I found http://www.mcmaster.com/#8975K142 <-- this 1/4" x 12" x 36" for ~$63 plus less than 10 dollars local delivery. I downloaded a DXF viewer and printed the plates half scale on a piece of paper and wanted to verify that the big plates are ~7x9" and the Z plate and X plate are 5.5x7" I haven’t acquired rail parts yet but I figure having the plates first would motivate me to buy other parts to start putting them together onto.
If you have a friend that can get it bootstraped for you, definitely get two sets. It never hurts since the demand for plates is very high. The plate set of 4 runs for $150 easily.
Also, this price looks cheaper than http://onlinemetals.com ($76.69 there)
I never thought about turning the plates like that. How much space between? I need to find out what kind of bits he has and could cut this with.
@Alex_Lee I may be new to CNC, but not material optimization. 
I managed to get all 4 plates on 15"x15" and 12"x20" sheets. But then I found this: http://www.ebay.com/itm/Lot-of-2-piece-T6-Aluminum-Sheet-Plate-6061-12-x-12-x-250-1-4-/261752570541?pt=LH_DefaultDomain_0&hash=item3cf1ab42ad which turns out to be less than $30 shipped to me, and the plates will easily fit on 2 12"x12"s. Here is a .zip of the .pdfs that show how you can move them around: https://drive.google.com/file/d/0B8umWeFlAdqlWDBrVW5kODE3RjQ/view?usp=sharing I made them with a graphic design program, so I wouldn’t recommend trying to turn them back into .dxf and cut them.