A do it yourself pickup bed liner can end up being just about the same as the better spray coatings from the big name liner pros. The best roll on bed liner won't cost nearly as much as a Rhino or a Line X though. Here are a few shopping tips and a few installation tips.
The truck bed liner reviews most often are just dealing with the better known brands of bed liner paint. The Herculiner and the Dupli-Color and the ones that are already familiar names. Most of the liners are a lot alike. You're going to get about a gallon of material to put a couple of coats on a pickup bed. It's mostly a polyurethane paint and some have some epoxy in it. Many of the liners include ground up rubber pieces in the coat to give a little texture to the finish. You may but mostly won't get much UV resistance in the finished coat. It will fade from black to gray over time. There are some options though.
For example Al's bed liner is related to Scorpion coatings. That's an outfit that is used by commercial installers much like the Rhino bed liner is set up. The Al's finish has a lot of different ways it can be used. You can make it harder or leave it softer. That way you can build finishes that vary like all those options from Rhino. You can color it any color and include metal flake in the paint if you want to. You can make it smooth or include texture. You can really make a finish much like whatever you want. This is a completely different approach and shows that the do it yourself coats need not be so limited. If you don't like the thinner coats which are mostly what you get with roll on bed liners, just get more paint and build a thicker finish. It's up to you. It's your money.
Here's the other thing to consider.
The Al's liner and the MagnaLiner products are both presented in reasonable manners. Emphasis is on the application methods. You can just roll the paint on over rust and do little preparation and the coating will not stay on and you will not like what happens. That seems to be at odds with how this paint is presented.
It doesn't take a lot of work to get it to stick. It does take some careful cleaning. It takes some serious sanding and etching. Do those and the paint will stay put. Just put it on any old way and you find that this is expensive paint but not miracle paint.
A DIY pickup bed liner works mostly because the right surface prep is done. Some of the paints that are available are a little bit different from the most promoted brands. You can get good results with any of these paints. To get happy results though requires the right surface prep and the right application methods and tools.