It's true that liner paint is just one of the ways to protect your expensive truck bed. A liner is almost a necessity if you're actually going to use your truck to haul anything. Even just hauling groceries is a quick way to scratch the factory paint on your truck bed. The truck liner paint is a way around that.
Scratched paint is a quick road to a rusty pickup bed which is the road to ruin of your truck. A professional spray in bed liner is a great way to protect your truck. But have you priced spray on liners lately? They aren't cheap.
An alternative to a pro applied liner is bed liner coatings you can apply yourself. There are many suppliers of bed paint including Herculiner, Magnaliner, Plasti-Kote and Durabak. These finishes are similar.
The diy bed liner is especially appropriate for older trucks with already damaged beds. The bed liners for trucks you apply yourself can really make your truck look great when combined with repairs of the existing damage to your bed. Your renewed bed may make the rest of your truck look shabby.
The supplies for a do it yourself liner are much cheaper than a pro bedliner. A professional liner may cost many hundreds of dollars while a kit for owner application is between one and two hundred dollars. Cost is the real benefit to doing it at home.
For that price you can buy the sandpaper for bed preparation plus primer and the actual paint finish itself. Most professional coatings are a two part sprayed "paint" which include a catalyst that guarantees almost instant drying plus the coating includes rubber granules to provide texture and cushioning. Your do it yourself liquid bed liners finish will be designed for application by brush or roller, though some can be sprayed with your gun if you wish.
Another plus to home application is you can just coat certain areas. You could apply a >paint coat just to the bottom of a bed or just to the side. You can custom coat parts as you choose.
A professional lining will be more durable than what you apply. There are two reasons. Firstly, the professional coating is sprayed with special equipment and is formulated to be fast drying and very tough and UV resistant. It's far beyond just paint. Secondly, The pro application is much thicker than a coating you apply. What you apply will be only a few thousandths of an inch thick where a professional liner may be up to 1/4 inch thick. The result is the pro liner can take much more abuse and still not be scratched down to the paint.
Another real key to liner durability is pre-paint surface preparation. A professional will prepare the surface properly because you are getting a durability guarantee. If you as the applicator skimp on preparation, your coating will flake off and fail. Surface preparation is hard work. First you must remove all the wax build up on the bed coating. Paint won't stick over wax. Then you must very aggressively rough up the existing paint. Finally you must prime the surface before applying the finish coat. Don't forget proper masking too. Preparation is the key to a great finish.
For a new or late model truck, look closely at a professionally installed liner. For an older truck, especially one with some bed damage, a do it yourself roll on bed liner can drastically improve the looks of your truck bed. Save money by doing it yourself and get the satisfaction of making your truck look better and last longer at the same time with truck liner paint.