Doc Blues
Beautiful
Al

Bicycle innertube, with a little electrical tape on the bottom.

Simms Vibration Labs has a wrap that provides a  sure grip and works when wet.

If we are talking cheap functional then there is a product called Wrap Seal for fixing pipes and other things.  It is 1" wide and 8' long in the role I got.  It is thicker and wider than electrical tape.  It has more of a rubber feel to it.  I have not used it for a bow grip, but it would work well for that I think.  It has a release paper on one side and it can be stretched a lot if you want so it should stay down well and mold well.  I have some, and I may try it out just to see.  I got it at one of the big box lumber stores.

the tape you wrap base ball bat or golf club handles great grip plus some cushioning