I need your help in solving one of my issue related to adding extra/custom price on subtotal on cart page. I have called a observer for checkout_cart_product_add_after and sales_convert_quote_item_to_order_item event and in which I am trying to add dynamic price from below code


This is allow me add in unit Price but I want to add in Subtotal of product. Also I have to tried to add price via custom options but it adds in Additional_optional field and not stored in info_buyrequest so might it not reflect to the subtotal price.

Please advise for suggestion.


  • Can you do it using promotions->shopping cart price rules? You can define your rule there to add your extra price.
    – Kishor
    Mar 10, 2015 at 5:37
  • No kishor! I want to add dynamically or product wise. So I need to do from observer.
    – Vick
    Mar 10, 2015 at 5:38
  • Try mageworx multifee extension
    – ladle3000
    Mar 10, 2015 at 17:34
  • Hey! Its paid extension and I want to done by programmatically I have create some dynamic custom options based on products and their price.
    – Vick
    Mar 11, 2015 at 5:18
  • Yeah, not everything is free in live. But maybe we cannot make it for less than what that kind of module cost. So it is either some kind of (payed) module or default Magento. Or create your own module
    – Jeroen
    Mar 12, 2015 at 19:18

1 Answer 1


You can accomplished this by overriding Mage_Sales_Model_Quote_Item via modules config.xml:


And then overriding the calcRowTotal()

class Namespace_Module_Model_Quote_Item extends Mage_Sales_Model_Quote_Item
    protected $customRowTotalPrice = null;

    public function setCustomRowTotalPrice($price)
        $this->customRowTotalPrice = $price;

    public function calcRowTotal()
        if ($this->customRowTotalPrice !== null) {
            return $this;

        $qty = $this->getTotalQty();
        $total = $this->getStore()->roundPrice($this->getCalculationPriceOriginal()) * $qty;
        $baseTotal = $this->getStore()->roundPrice($this->getBaseCalculationPriceOriginal()) * $qty;

        return $this;


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