Yeah, no sense in buying a 25 lb. bag of shot (especially at today's prices) when you only need a couple of ounces. A box of shells with #9 shot will do you just fine. Even better just talk a local bird hunter out of a couple of shells.

You actually could use a wheel weight or two instead. Just hold the steel clip with a pair of pliers and melt the ends of the weight with a standard propane torch over the slots and let the lead drip in as it melts. Make sure to use some OLD style (steel wheel) lead wheel weights. Newer weights have zinc in them and you don't want to be breathing the fumes from melting those.  I am assuming that the crank wheel is an aluminum casting? The lead won't stick to the aluminum and you could knock it out after it cools to trim off any excess weight. The only thing I would worry about though is possibly discoloring the wheel from the heat. Using the shot would be the safer way to go.