A friend started his own business applying spray in bed liners for the local dealers and he makes 90% profit on what he charges. On Amazon the U-Pol Raptor Black Urethane Spray-On Truck Bed Liner Kit w/Free Spray Gun, 4 Liters sells for $125 and it would be very hard to screw up a DIY spray job on a truck bed.
I have always been able to get the dealers to provide me with a free spray job or a free plastic bedliner when buying a new truck. They make more profit from the sale of a pickup than any car or SUV that they sell and they want to make the sale. They also know that you can go to another dealer and buy the same truck so they need to sweeten the deal.