It is my practice to have the shafts (as long as they're good) treated with Dry Film Lubricant. This doesn't prevent them from spinning or rotating, but does significantly reduce their friction to the tunnel. I may tinker with a bushing fix, but...
The problem as I see it is not the production of the bushing, but the reaming of the tunnel to accommodate the bushing. The shaft has to remain the same OD, so there's essentially no room left without enlarging the current hole. Turning a bushing on a lathe and pressing it in is small potatoes. Enlarging the hole (requires a special fixture to hold it on a mill) and a very long reamer (expect that to cost over $200 bucks alone) and the machine time, and now you're talking about a pricey repair. Even amortized across 20 covers, the setup and machine time is probably 4 hours for the milling. The bushings another 1 each (8 by my count) and now you're into the $600+ range even at super cheap shop rates.
So I'm not sure it can be done cost effectively. Not without using a CNC lathe to cut the bushings (then you have their machine time and programming to account for too) and some willingness to tinker with it.
I put this (I do think its a very good idea by the way) into the same category as remaking the engine mounting bolts out of stainless. But that too costs well over $100/set due to the machining and material. If you need to make them for yourself, thats one thing. But to make and resell, well we all know how cheap some CB owners are