There is a smal gun club where I live that has a bunch for M-a1, and at least 2 for L-a1. Could not find any for S. (I just bought an M one to modify it). Dont know if they will ship but if anyone is interested I'll get you the number or get it and send it your way. They are selling at $30.00 + 11.5%tax = $33.45(about). Plus whatever shipping which should not be more than $5.00 to USA. The place is called "Executive Gun Shop" in Guaynabo, PR USA.
+1 787-287-1919. Ask for Rafa, he is the owner and should be able to help with those weights