Are there any aftermarket makers of door sills, either metal or plastic? My shiny white Sidekick sills are in good shape, and I'd like to keep them that way.

On my old tracker, I bought some skateboard grip tape from a skateboarding shop, and cut it to size and stuck it on. it helped with the slippyness as well as protecting the paint(not that I was trying to preserve it  the truck was pretty rough)