Add to Cart allowing hidden prices to be seen

Hi All

I have a problem i hope someone can help me with

I have my website set to only show pricing when visitors to the site are logged in.. which works in the most part, however, the add to cart button is still on the site and if you click it the product goes to your shopping cart and displays the price there...

I found this fix on the forum

http://forum.opencart.com/viewtopic.php?t=46767

and wondered if it was still valid for 1.52?

or if there was another way to fix it, by way of a vqmod etc? i see a few that work for that but only if its an out of stock issue

any help would be hugely appreciated

thanks

steve