I don't think they can be bought pre-made, but you can make your own quite easily like this, which looks like this:

http://scriptasylum.com/forumpics/balancer_Y.jpg

You should step up to a robinson spur and dont run any slipp. I have a bunch of RR spurs but have only used one in three years, the delrin is great.

but as brian said. there will be more problems with the steel spur gear.

brian do i have to mod the thing that goes into the balancer?