function zcc_enter_price_check(value) {
	if (isNaN(value)) {
		alert('You must enter a numerical value only');
		document.getElementById('add_to_cart_button').disabled=true;
	} else {
		if (value != '') {
			document.getElementById('add_to_cart_button').disabled=false;
		} else if (value == '') {
			document.getElementById('add_to_cart_button').disabled=true;
		}
	}
}