If you are looking for cheap bed liners for trucks then you just have a few choices. The three best options are the plastic bed liners, truck bed mats and the do it yourself bed liners. Here are how these compare.
With plastic bed liners like the ones from Pendaliner or Duraliner you can get a lot of liner for just a little bit of money. These liners can now be shipped to you too in some cases. These are liners that will cost very little more than a do it yourself roll on bed liner.
The problem with plastic drop in bed liners is what they sometimes do to trucks. With just a little movement in the truck bed you can get weariing away of the bed paint under the liner. The liner is wearing away the paint you see. This is a disaster. You get any water under the liner and mix it with bare paint and you get the start of rust and corrosion in the bed. I'm not saying that this will always happen but it does quite often. I've seen it and you probably have too.
This makes the plastic liner less than the best option in the low price category. There is the DualLiner drop in liner that does not have that problem because it uses a rubber bed mat on the floor. That solves that issue but the DualLiner products are a bit more pricey. Speaking of rubber bed mats though...
For nearly nothing you can get pickup truck bed mats either of carpet or of rubber. These only cover the floor. But that is where most of the trouble is anyway. Custom mats are good at soaking up impacts and are tough to cut or scratch as well. On top of that the better mats will really last too even under tough use. Mats are a really good deal for protection of bed or even to go over more costly liners as liner protection. Then there is the final liner option in the lower price bracket...
The do it yourself bed liners are a popular pick. You can do some of the work yourself and end up with a liner coating that looks just about like the better spray in bed liners like the Rhino Liners or the Line X. The coating is easy to put on but there is a catch. It seems a lot of people don't catch on to this either.
The hard part to putting on liner paint isn't the actual application. It's getting the surfaces to be coated ready to coat. Most of the time pickup beds have wax on them. Put paint over wax and it will not stick. It won't stick to grease and oil either.
In fact from the stories going around a lot of liner paint gets labelled as no good when it was the installer who was really at fault.
The better liner paint options to me look like some of those that aren't really all that well known. Look at Al's Liners and look at the Magnaliner for some quality products with some features that set them apart.
The options in cheap bed liners for trucks are few, but there are some good ones.