dont use http to get the file,just call file directly
use this code
$url = "feeds/price.xml";
You can also use this code to get all the file in feeds directory and get all result in $Price variable
$Price = "";
foreach (glob("feeds/*.xml") as $filename) { //Getting all xml files from feeds direcotry
$xml = simplexml_load_file("feeds/".$filename);
$Price .= $xml->xpath("//PRODUCT[@CODE='". $product_id ."']");
}
print_r($Price);