I can't imagine any genuine wholesaler charging a joining fee before supplying a price list, they would be out of business in no time. Wholesalers rely on selling to retailers, and as a retailer I can tell you that I would never pay for a wholesale price list, and I would suggest that not many would.
Trying to charge for a list that others will freely give in order to do business would quite simply be detrimental to their own business.
My guess, they are not a genuine wholesaler, just a middle man brokerage type operation without any margin on their products, and that's how they are generating their income.
I must admit that they sound more like a drop shipping company pulling that kind of stunt, and one to stay well away from no matter what they are.
A genuine wholesaler may require a tax id to do business with you, but that is to ensure you are a legit retailer.