/*
 Theme Name:   Woodmart Child
 Description:  Woodmart Child Theme
 Author:       XTemos
 Author URI:   http://xtemos.com
 Template:     woodmart
 Version:      1.0.0
 Text Domain:  woodmart
*/
add_filter( 'woocommerce_is_purchasable', 'wpa_asargaa_is_purchasable', 10, 2 );

function wpa_asargaa_is_purchasable( $purchasable, $product ){
    if( $product->get_price() >= 0 )
        $purchasable = true;
    return $purchasable;
}