I've got the Rhino Liner in my truck... I would never do a plastic liner because I can't stand the slipperyness. It's really just a matter of opinion and use as to which liner is better than the next. My last truck had a Linex, and it was good, but I like my Rhino MUCH better. It's a much thicker, tackier, durable liner, IMO. But they were both sprayed at different places, so installation may have something to do with the different levels of quality.
The REAL bottom line is to make sure that it is sprayed in by someone who knows WTF they're doing! It would be worth a couple extra dollars to me to have a good liner rather than save a few for a liner that doesn't do its job. Ask around with people you know who have bed liners that you like, and see where they went. Just my $. 02.
To answer the original question, I paid about $450 for the Rhino under the rail.