Magento: Add Fixed price to same Product for a Multiple Qty in cart

Actually I want to set custom select Shipping Time for a perticular product when it add to cart from Category Page,

That’s why I found some solution for that add custom value to the Row Total of product

For that

A) Open code\core\Mage\Sales\Model\Quote\Item\Abstract.php

Find, Function calcRowTotal()

You can see this lines,

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

Simply, Add your custom value here

$temp = 10; /* Now $10 inserted in to the Row total of Product in cart */

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

Here the Basic idea for, Where to change for add custom value of row total of product
you can also set this dynamic as per your requirement.