I do that too. Any time a tire shop balances a set of tires, they remove the old weights and throw them in a bucket to be recycled (Lead is unfriendly to the environment, so they don't want to trash them).

Just go to your local tire shop and ask them for a handfull or two. Pick up a cheap pot at the local Good Will Store (I use an old cookie sheet) and melt them down with a torch. Once they melt, you can remove the steel clip with a pair of pliers. You can even shape it a little as it cools.

They even have their weight molded right into them