Bed Liner question: How much for one?

[TIMSPEED]

I am considering getting a Spray-On bedliner done to my truck. They quoted me $300 for an under-the-rail job. Real quality place...do you think that's too much $$? I'm considering getting it done, becuase my bed looks like CRAP! (surface rust and paint's chipped to hell) After I got it done, I would simply pull the sides of the bed off and then sand/primer/paint then and stick em back on...that way, at least HALF of my truck will be painted
But seriously, you guys with Spray-On bedliners, how much did you pay? I'm wanting to get this done and then put carpet in there and possibly have a camper shell for it, if I ever wanna take it somewhere, so i can sleep in the back