I have Interlake brand tear drop style uprights (3 of them), 14 ft high, and 40" deep total, with 24 ea, 8 ft lightweight open bottom beams. The beams have shallow "notches" on the upper inside for the plywood/wire grid/boards to fit into.
On some shelves, I used 2x6's like Home Depot does on their pallet rack/shelving but with the shallow notches, the boards stick above the edge of the beams. On one shelf, I used scrap ends of 5/4 deck boards that were long enough to allow me to cut them down to 36" to fit into the beam notches, they are nearly flush with the top of the beams, on the rest, I carried home pallets that full 55 gal barrels of chemicals come on, and I cut the heavy rough cut boards off the top of the pallets, they too are about 5/4 and worked real well. Plywood is not heavy enough and will bow down unless it has cross supports.
The shelves are 2 ft apart, and the bottom one is far enough off the floor to allow me to get a broom under it to clean. I use the 10 ft rollingwarehouse steps to access the upper shelves (to the right in the pic) I just roll it back and forth in front of the shelves.
Underneath the second shelf, I added some cross braces of wood and use this area to slide 10 ft to 20 ft sections of PVC pipe, angle iron, etc into for storage.
I ended up putting them in front of my sidewall skylights, but the skylights didn't work out as well as I planned anyhow.
I paid about $400 several years ago for this, a little high but I needed them.
Charles
My main bench is based on a pallet rack. I also have a 4' one that I use on a temporary basis. I can assemble it and knock it down in minutes. 
