Anyone wanting to make a living selling parts for vintage motorcycles has a problem. Norton is the easiest because AN, RGM, and Norvil all have parts and AN has almost all.
Unfortunately, those three do not have real dealer/distributor accounts. So, when you buy from them and you are outside the UK, the small “dealer” discount you get is eaten away by shipping costs, especially if you buy any large parts. This means that you cannot compete with them and make money unless you charge huge…