You can get raptor which is made by u-pol for about $135 at an auto paint store and do it yourself. I did my buddys daytona and its still holding up just fine. The cool thing about it is its tintable so u can color match it to your truck if you want. I plan on doing mine once i get some time to do some more work on my truck. Once I do Ill be sure to post up some pics.
zbart makes rust proofing undercoating for cars and trucks back home in chicago they have been around for over 30 years and we used them on all our cars. if they do bed liners to than I'm sure its not bad