Most legit suppliers will require certain criteria to register as a business customer, however I would not suggest ever paying for wholesale access.
Anyone who is trying to charge you to see wholesale prices are not providing you with genuine wholesale, they are making their cash out of your membership fee.
Some may set their MOQ prices for viewing, but wholesale prices are based on volume, and most can't provide an accurate price until they know what you want, and the volume you want to buy it in.
Create a dialogue with the sales department of any suppliers that interest you, they'll be more than happy to assist I'm sure.