Source for ceramic bearings?

Has anyone got a good source for those ceramic bearings Flipsky uses?

Locally I can only find some at really high prices and AliExpress has loads of vendors with unknown quality.

Most people I know, including myself, switch to stainless bearings, since they will last longer and are more telling before they fail.
Good source in Germany is https://www.kugellager-express.de
They seem to sell ceramic too