dump.php

<?php

set_time_limit(600);
define('MAGENTO_ROOT', getcwd());

$compilerConfig = MAGENTO_ROOT . '/includes/config.php';
if (file_exists($compilerConfig)) {
    include $compilerConfig;
}

$mageFilename = MAGENTO_ROOT . '/app/Mage.php';
if (!file_exists($mageFilename)) {
    if (is_dir('downloader')) {
        header("Location: downloader");
    } else {
        echo $mageFilename . " was not found";
    }
    exit;
}
require_once $mageFilename;
Mage::app()->setCurrentStore(Mage::getModel('core/store')->load(3));

$collection = Mage::getModel('catalog/product')->getCollection();

$data = array();
foreach ($collection as $product) {
	$data[] = array(
		'sku' => $product->getSku(),
		'price' => $product->getPrice(),
		'special_price' => $product->getSpecialPrice(),
	);
}

file_put_contents('product_price.json', json_encode($data));