Add custom price on frontend using admin side attribute

config.xml

<?xml version="1.0"?>
<config>
  <modules>
    <Test_Test>
      <version>0.1.0</version>
    </Test_Test>
  </modules>
  <global>
    <helpers>
      <test>
        <class>Test_Test_Helper</class>
      </test>
    </helpers>
<models>
 <test>
<class>Test_Test_Model</class>
<resourceModel>test_mysql4</resourceModel>
 </test>
</models>
  </global>
  <frontend>
    <events>
 <catalog_product_collection_load_after> <!-- identifier of the event we want to catch -->
        <observers>
          <catalog_product_collection_load_after_handler> <!-- identifier of the event handler -->
            <type>model</type> <!-- class method call type; valid are model, object and singleton -->
            <class>test/observer</class> <!-- observers class alias -->
            <method>catalogProductLoadAfter</method>  <!-- observer's method to be called -->
            <args></args> <!-- additional arguments passed to observer -->
          </catalog_product_collection_load_after_handler>
        </observers>
      </catalog_product_collection_load_after>
    </events>
</frontend>
</config>

Observer.php

<?php
class Test_Test_Model_Observer
{
public function catalogProductLoadAfter(Varien_Event_Observer $observer)
{
$collection = $observer->getEvent()->getCollection();
foreach ($collection as $product)
{
$produ = Mage::getModel('catalog/product')->load($product->getId())->getData('discountatt');
$originalprice = $product->getPrice();
$customprice = $originalprice+$produ;
$product->setPrice($customprice);
// $product->setData('my_price',$customprice);
}
// echo '<pre>';print_r($produ); exit;
// $product = $observer->getEvent()->getProduct();
/*$originalprice = $product->getPrice();
$product->setPrice($customprice);*/
}
}