Code:
{ if $product.appearance.has_market_price && $product.appearance.market_price_discount gt 0}
<span class="product-taxed-price">{$lng.lbl_market_price}: {include file="currency.tpl" value=$product.list_price}</span>
{/if}
this is the code that shows it but it's conditional and will not show it if you put 0 as market price on product modify page in admin. Try clearing the cart cache
www.yourdomain.com/cleanup.php - see if it works