TorontoBuilder
Sapientia et Doctrina Stabilitas
at the price you can buy 4 or 5 wheels. I am buying the kit to increase the drill sizes up to 3/4" too for peanuts.I think they could last a very long time. Especially if they are dressed as needed. But if you intend to use it extensively, I'd get a backup wheel or two. Then again, I have backups for a lot of things that I've never needed so my advice should be suspect.
plus, economics says, sell enough you create a long term demand for consummables, and China loves to sell consummables.