I made my own out of angle iron. I cut them to length and put a curve on the back end so it matched the bed profile. Then I marked the cutouts for the stake holes and cut them out with a plasma cutter. I found some chrome bed tiedowns to put in the cutouts so that you can't see the rough cuts from the plasma cutter.
I was worried about rust so I didn't want to put bolts through the top. I put a thin rubber material under the top and used stainless steel bolts to attach it to the inside of the bed. Its been that way for about 8 years and all you can see is wear on the black paint I used.
I also have a headache rack and cargo box, which are bolted right on top of the angle iron bed caps.
Bruce