Hello -
You are going to have to use an ACL setting for this. Your Wholesale users can be mapped to "Author" for Joomla class, and then you set the permission level on the Wholesale page to "Special" which will hide it from Registered members. Alternatively, you could get JACLPlus or one of the other ACL plugins that works in Joomla 1.5 to add granular ACL control. These should work okay with Virtuemart so that you can use two different custom ACL groups so that Registered can see one menu item and Wholesale can only see the other one.