You MUST have established distribution BEFORE proceeding with Costco. Strong distribution of your product(s) is non-negotiable, as Costco will not work with your company if they are, or would become a majority of your business sales.
So how much is enough? This will depend on which avenue of Costco you are approaching (ie: Costco In-Store, Costco.com, Costco Road Shows, etc.). Obviously, your distribution backing should match the avenue that you are pursing. In other words, if your company only has ecommerce sales, you are not likely to land an in-store account.
If you believe your distribution is sufficient for Costco, and would like more information about HOW to approach Costco, contact VendorCo at [email protected] or (949) 326-8909.