This subject has been discussed a few times here in the Tacoma Forum. Fact is (tacomaman06) is right in regard to the cost. It can be quite expensive, as it's my understanding that the bed has to be "prepped" to get the Line-X material to stick.
If you're really interested in the possibility of doing this, may I suggest...
#1 try doing a search here in the Tacoma Forum for Line-X. If that doesn't produce the results you're after,
#2 try PM'ing TS.com member (123Gone). He's a Line-X dealer in Texas and is...
VERY... knowledgeable regarding all things... well...
Line-X-able.

If memory serves me correctly, I think he's actually tried Line-X on a Tacoma bed, or at least a piece of the same material. There's
NO doubt in my mind he can help ya...

:tu:.
Dave