Tab,
The cedar strips on the sides is a good idea. The bed something like 49 inches, which is short of the 48 inch width of a sheet of plywood.
I bought my yellow pine at Shamburgher lumber on Mockingbird lane in Dallas. I dried them, ripped them to width and used a router/tablesaw combination for the steel strip grooves. All in all I think it cost under $150 to do the bed.
