Решение для оптовой покупки - JoomShopping

 <script>
        function SumAll()
        {
		var product = document.forms.product;
		var a=parseFloat(product["freeattribut[1]"].value);
		var b=parseFloat(product["freeattribut[2]"].value);
                product.quantity.value =  a+b;
        }
        </script>

 <input type="submit" class="button" value="<?php print _JSHOP_ADD_TO_CART?>" onclick="jQuery('#to').val('cart');SumAll()" />

 $product->freeattributes[$k]->input_field = '<input type="text" class="inputbox" size="40" name="freeattribut['.$v->id.']" value="" />';

  $product->freeattributes[$k]->input_field = '<input type="text" class="inputbox price_td" size="5" id="freeattribut_'.$v->id.'" name="freeattribut['.$v->id.']"  onchange="document.getElementById(\'quantity\').value = parseInt(document.getElementById(\'quantity\').value)+ parseInt(this.value);" value="" />
				<input class="quantity-minus" type="image" img src="/components/com_jshopping/images/minus-16.png" onclick="var qty_el = document.getElementById(\'freeattribut_'.$v->id.'\'); var qty = qty_el.value; if( !isNaN( qty ) && qty > 0 ) {qty_el.value--;
				var qty_all = document.getElementById(\'quantity\'); qty_all.value--;}
				return false;">
				<input class="quantity-plus" type="image" img src="/components/com_jshopping/images/plus-16.png" onclick="var qty_el = document.getElementById(\'freeattribut_'.$v->id.'\'); var qty = qty_el.value; if( !isNaN( qty )){ qty_el.value++;
				var qty_all = document.getElementById(\'quantity\'); var qtys = qty_all.value; qty_all.value++;}
				return false;">
				';