Cut-off wheels and flap discs...

[Roberts68]

As for cutoff wheels I think the ones I used to get from the Mac man that were silkscreened Mac 20000rpm max were the best. Some el-cheapos with a reinforcing grommet were good too.

The worst may even be irregular thickness. How about a 20000rpm explosion of abrasive material at arms reach, no thanks!

You might try MSC direct and set up an account with them in 5 minutes. Tell their rep you do not want crappy ones. They've been really good to work with and usually give like 25% off initial orders regardless of the size of the order.