Tony Clayton makes covered wire. He’s here on this site. I’d check him out here and message him.
Also Darryl Hudson always has some replacement wires. He’s a machinist and does very good work. Check him out at Hudson Custom Machining.
There are a few sites online, but to be honest Tony’s wire is far superior, Darryl’s is a step above the online stuff as well.
You should definitely consider joining AFCA here. It’s proved valuable to me.