function makeSum(obj) {
	price = obj.options[obj.selectedIndex].value + "";
	priceField = obj.id + "_price";
	if (parseInt(price)) price = "£"+price ;
	document.getElementById(priceField).innerHTML = price;

//	alert(document.getElementById(priceField).value);
	theSum = 0;

	theSum = theSum + parseFloat(document.dyo.cooler_model.options[document.dyo.cooler_model.selectedIndex].value);

	for (i=0; i<modelOptions.length; i++) {
		if(parseFloat(document.getElementById(modelOptions[i]).value))
			theSum = theSum + parseFloat(document.getElementById(modelOptions[i]).value);
	}
	//alert(theSum);
	if (document.getElementById('total_sum_design')) document.getElementById('total_sum_design').innerHTML='Total: &pound;'+fmtMoney(theSum, 2, '.', '' );
;
}
fmtMoney = function( n, c, d, t ) {
	var m = ( c = Math.abs( c ) + 1 ? c : 2, d = d || ",", t = t || ".", /(\d+)(?:(\.\d+)|)/.exec( n + "" ) ), x = m[1].length % 3;
	return ( x ? m[1].substr( 0, x ) + t : "" ) + m[1].substr( x ).replace( /(\d{3})(?=\d)/g, "$1" + t ) + ( c ? d + ( +m[2] ).toFixed( c ).substr( 2 ) : "" );
};