[RuralRoute C-30]

Just an idea about the foam, not sure how much your covers alone cost, but foam is cheap and would try not to spend a lot on a kit where they may be overselling you on the foam and the covers too.

Foam can be bought from a variety of sources. One here is a local bed store where they make the beds as well. A friend wanted to restore his hunting/camper trailer beds and they gave him enough scrap to do the job for free except one piece he wanted specific. And that was still cheap.