I gotta disagree with you. The stuff you get at wal mart - Duplicolor Bed Liner is kinda junky. I've heard of much much better results with Herculiner or this stuff called "warnex" paint from over sears.Spend the extra money for Herculiner, the Duplicolor stuff has already chipped for me a few times and i've only used the speakers like 3 times
However if they aren't being moved I would actually use the duraliner stuff with a REGULAR roller to give it a non textured finish but better than paint.
-Josh Billings