I am not fully understanding what it is you want ...

You can have several setups:

1 customers come to the site and shop as a guest or when logged in
Customers can see the whole site with prices, whether or not they are logged in to the shop

2 customers come to the site and must login to shop:
A Can see the site with prices
B Can see the site without prices
C Cannot see anything until logged in

3 customers come to the site and must login to shop, and they need to be approved
A Customers can see the site with prices
B Customers can see the site without prices
C Cannot see anything until logged in
D Cannot see anything until approved

Can you give a bit more detail on exactly what it is you want?

Also, what version of Zen Cart are you running right now?

Clean install or an upgrade?