I don't have a lot of problems with the bushes wearing down either. The cheaper ones from China need to be replaced every so often but are not expensive. Then again if you practice and keep the tools off the bushes there is not a problem. I only use sandpaper for the final trim to the bushes and if you are careful their contact with the bushes is very minor and light.
I only use delrin bushes for applying the CA and they clean up easily with the dry CA breaking off with slight pressure from a pair of pliers. Some will shudder
You can get a pair of electronic calipers from Aldi at the moment for around $14. They are good value for the cost.
If you want much tougher bushes you could go to the metal turning site on this forum and ask if anyone is interested in making them you but I doubt they will be cheap.
Greg