The only reason I don't use the Lizard skins or other things is because I like taping over the knob for extra grip. I really don't care about the grip, and have taped the knob on a few and put the lizard skin back on.
I might try one of these. Won't be putting one on all my bats though.
I just found some heat shrink tubes at work that shrink from 1.75" down to 0.32". I'm trying one out on a cracked bat, I'll let you know if I've found a cheaper alternative.