Get Finaly price from product for customer group
<?php
ini_set('display_errors', 1);
error_reporting(E_ALL);
//$path_parts = pathinfo($_SERVER['SCRIPT_FILENAME']); // определяем директорию скрипта
//chdir($path_parts['dirname']);
//require_once $path_parts['dirname'] . '/app/Mage.php';
require_once ('app/Mage.php');
Mage::app();
define('ROOT', Mage::getBaseUrl(Mage_Core_Model_Store::URL_TYPE_WEB));
$now = Mage::getSingleton('core/date')->timestamp(time());
$websiteId = Mage::app()->getStore()->getWebsiteId();
$customerGroup = 4;
$productId = 3854;
$data = Mage::getResourceModel('catalogrule/rule')->getRulePrice($now, $websiteId, $customerGroup, $productId);
Mage::log($data, null, 'checkprice.log');