Most any tire shop will give those weights away, Josh. They have to save them up & dispose of them properly anyway. Just bring a few buckets with you to any local tire shop, ie; Discount, Les Schwab, Sears, they will all have them. Probably way more than you need!!
Only caution is that when your melting them down, do it outside & don't be breathing in the smoke....... it won't kill you quickly but it might make you do stupid things.