Only a short time ago hairbrushes and brushes of all sorts were handmade by local families. Children and parents would sit together around the table sorting bristles and making brushes.
Our goal is to make it possible. To retrieve lost skills and hand them off to people that are interested in providing the services to their local communities. To that end I have begun researching brush making and welcome any additional information that anyone with better knowledge than I can provide.
The necessary components for a handmade brush (and I am thinking hairbrush here though the varieties are almost infinite) are a handle and bristles. From information scattered in random places over the internet it seems the handles are usually made from some sort of hardwood or bone. The woods I found range from ebony to satinwood, beechwood or even maple. Bristles for hairbrushes were unanimously Boar - though other animal fibers are used for a variety of other brush types.
In north america finding local hardwood should be fairly simple - a quick google search found me several mills and suppliers within a reasonable distance. If wood is not available then try for horn.
Boar bristles on the other hand are going to be challenging to procure from anywhere near local. China and India seem to hold the Bristle supply for the entire planet. Boar bristles also require some levels of processing (boiling and steaming repeatedly in such a way that the bristles remain straight). Another google search found me a wild boar farm in north america - and though it is by no means as local to me as I would like it it is at least still on the same continent. A nice conversation with the farmer and he will be giving a boar a quick shave in the spring when they are ready to shed their winter coats.
Each individual who takes up this trade in their local community will have to come up with their own techniques for making their own quality products and find their own (as local as possible ) materials. Perhaps they should also take up Wild Boar farming ;)