Keep the shears for the joints but watch out for bone shards, because cheap shears can chip and leave little bits in the meat that you won't catch until a customer bites down. That's the one thing nobody warns you about with the shear method. A $12 pair works fine for wings and backbones, but check the blades for nicks after every few birds and toss them once they start denting.

How rusty we talking, like flakes or just surface?

Word of mouth beats flyers every time. Have Gus bring his wrench to a Saturday market demo and fix something live, since people trust a guy who can actually do the thing. Get the local paper to run that story and the line will be out the door.