Take a look at egun.de.
All done by bank transfer but excellent service and not experienced any problems.

I recently bought 2000 once fired RWS .22 Hornet cases for re-sizing to .17 Hornet.
All came out like new when cleaned, and re-sized and fire formed without issue.


A few vendors sell mixed bags of 500 or 1000 once fired brass for around 100 Euros. You should find a few hundred of the same make in a batch that size.