Your best bet is ebay or amainhobbies.
BTW my matrix FRE is for sale its in new condition new internals in the diffs. It has almost every part for it. Shock shafts hubs arms diff stuff tony screw kit also have some stiffer springs for it also. no tires just roller. PM me if interested i have a good trader ratings on a few other sites. Just let me know and i can send them to you.