[GTALUG] (very off topic) quality die grinder bits

Hi all, Very off topic, but I'm fed up. I sharpen my lawn mower blade with die grinder. Problem is, all the bits that I bought from Canadian Tire, Rona, and Home Depot, they all wobble. Except for one bit. And, that has been used so much that I need a new one, now. If anyone has die grinder, what brand of grinding bits do you recommend? --