You can still purchase new 1" and 3" static master brushes and 250 microcurie replacement cartridges from Amstat Industries, Glenview, IL, Toll Free (800) 783-9999.
These are the finest negative dust removing brushes available. There is still a thriving antistatic alpha particle-ionizing brush industry here in the US due to the many uses of these brushes in biotech. I use these in tandem with the visible dust arctic butterfly electrostatic brushes that are easily available for dslr sensor cleaning. Buy a number of arctic butterfly brush attachments, and keep the ones you use for negative cleaning separate from those you would use for sensor cleaning.