There's a man, that everyone calls "Mr Zenon". Mr Zenon has a hobby. He's a collector. Collector of broken 'Mechs, salvaged directly for the battlefields. He's doing it himself. How it's possible, salvage is an important resource. Mr Zenon has a Battlemaster (BLR-3M BattleMaster Rogers replica) with heavy support, so he gets what he want.
Say you want some spare parts right away. He has them, but he won't sale them. He's a collector, so you can trade. Now he may be interested is ER PPC, or SRM6 with Artemis, you never know. If you have those, you may talk.
Where is a war, Mr Zenon will eventually show up with his workshop. Don't forget to look for him, he may be valuable.