actually the stuff is sprayed with a low pressure shoultz gun, as far as i know all the different types can be sprayed or rolled.
in some circumstances i like to roll sometimes i like to spray.
the spray gives a nice even coating, the roll you can be creative.
the hippo stays flexible which is nice as well as you can get tintable which is really a bonus if you are matching a color of a truck.
i have paid as little as $69/kit or as high as $149/kit. DO NOT TRUST the posted coverage, pure BS. shop around, keep an eye for a sale and buy 2X what you think you need and you could possibly still be a bit short.
it is great for sound deadening, if you have rough loads going into the bed, if applied correctly then it bonds wickedly and is nice for those rainy places.
but, be careful using it on something you will be keeping for a long long time as it can be a bitch to fix down the road. well, that is my suggestions anyway, others will vary.