[shan]

Take a look at buy_now.tpl

find this

{* $Id: buy_now.tpl,v 1.8 2003/11/14 14:41:51 svowl Exp $ *}
{if $js_enabled}
<table border=0 width=100% cellpadding=0 cellspacing=0>
{if ($active_modules.Product_Options ne "" and $product.product_options) or $product.price eq 0}

notice the

or $product.price eq 0

at the end