If your talking about 50 VGA cards or more then perhaps you can contact a AMD partner. AMD doesn't make VGA cards except for the FireGL. The AMD Partners you could contact are Sapphire, PowerColor, XFX, Asus, Gigabyte, MSI, HIS. If the amount is too small they will send you to a distributor or a reseller.
If you mean the actually GPUs good luck the new ones are highly allocated and the chance of AMD wanting to add a new OEM may be slim. There will be lots of requirements and money required you'll need a good lawyer and accountant to go through all the paperwork, Good luck.