This list isn't a complete one by far, but only contains some unicycle manufacturers and traders I know myself and made some experiences with. That means, it's likely that a brand is not listed, if it's not available in Germany.
Brian Dubé from New York was the first one in the world to produce juggling props for sale.
Henrys from Karlsruhe is the manufacturer of clubs and diabolos in Germany. Of course there are other manufacturers producing clubs or diabolos. But Henry's props are the most spread by far and they are said to be the best one. According to clubs I can confirm that.
The very first clubs manufactured in Germany have been made by Jonglerie in Berlin.
Pappnase has been the very first juggling shop in Germany. Besides their head quarter in Hamburg, they have subsidiaries in Munich and Frankfurt.