Hi,
It is obvious this issue has to do with Virtuemart Configuration, you have hided the prices from non-logged in users.
(non-logged users are technically called "-anonymous- shopper group" in Virtuemart)
If you have looked at forum.virtuemart.net, you would find solution instantly though.
To enable price showing for "anonymous shopper group" browse your Virtuemart Backend, and go to:
Orders & Shoppers --> Shopper Groups --> Select -anonymous-
Then see the screenshot:
Cheers.