You can add new catalog pages with the same items but with wholesale prices.
- Create a Links page and name it "Wholesalers Only" to link to all of these pages.
- Password protect the links page and all the wholesale catalog pages with the same password.
- Hide the wholesale catalog pages from your menu.
In the end, your visitors see a link for Wholesalers Only on your menu. If they are a wholesaler, they can enter in the password you give them and then access the wholesale prices.