Bolted Ball Valve

[Amber Gold]

I have an older 2" bolted ball valve (similar to the link below) that leaks when it's open. Does someone make a rebuild kit for them? Where's the cheapest source for these? I need to buy a couple more.

Thanks

http://www.grainger.com/Grainger/BANJO-Ball-Valve-1MKK6?Pid=search