See the Marc Parness website. These are $105 from Marc. The tools are really popular and special cones make it specific to wheel size. I got the ones that fit the GTS and other 12" wheels (Model VSP12A). Interestingly, Marc credits Jesse for helping him develop it for Vespa.
You can buy different cones from Marc Parness for balancing other brand motorcycle wheels.
The high quality Marc Parness wheel balancing tool gets high marks in reviews from many different sites and motorcycle forums. I think it was originally developed for BMW wheels.
I also include about 60 5 gram weights that you need for balancing. The plastic box is not included.
Its pretty easy to use.
$75 including shipping in the lower 48.
Here's a Youtube video by StickyFrog of Old as Dirt (I think) balancing a wheel with the Marc Parness tool. URL:www.youtube.com/watch?v=8y0oAU8Vxyg