WANTED – TM/WELL R4 MP7 Gearbox or shell

Looking for a TM or a WELL R4 MP7 Gearbox or just the shell as mine has cracked.
If you’ve replaced one for a HPA build, or have a spare (not likly), or know where I can get a one that’s not half the price of a new gun, or even better a new shell not made out of pot metal, please let me know.