It probably would have been cheaper to buy it as a kit, but not nearly as easy on the wallet. By buying the parts at O'Reilly I was able to pick them up a few pieces at a time as I could afford them.
I replaced a few individual pieces last year when I had it aligned, so a kit would not have worked well for me anyway.
I went with rubber because I hate squeaks, and because the truck rides bad enough already.
Slonaker