Contact Tab

Please help! I’ve posted this to jobs board without a response.

I want visitors to be able to view listings but not be able to Contact Owners until they have paid for a package.

When a visitor (who hasn’t paid or isn’t logged in) clicks on Contact tab a message should come up (preferably as an information box so it doesn’t take them away from listing) stating that they can’t use ‘Contact’ tab until they have paid for a membership or logged on to existing membership.

The information box (if possible) should have a link to the membership page.