Searched for the forum and can't find an answer. BUT instead of saying something is $0.00, how can I just label it as FREE? It sounds better too. :)
You can use a template override to change how a price is displayed by using the "products:prices_block" hook.
I.e. addons/my_changes/hooks/products/prices_block.override.tpl
with content similar to:
{* don't add anything outside of the if condition *}
{if $product.price|floatval <= 0.00 }
{* Add your custom block code here *}
{* otherwise, standard prices_block code will be used if there’s no output from this file*}
{/if}
You can see the original code in design/themes/[your theme]/templates/common/product_data.tpl. I.e. for how to handle settings like zero price action and hide add to cart settings.
As alternative you can override the following template
design/themes/THEME/templates/common/price.tpl
It is used to display all prices in the store