HTML - agarrar un dato de una pagina ajena e insertarla en la mia

<?php

$client = new SoapClient(null, array('location' => 'http://www.banxico.org.mx:80/DgieWSWeb/DgieWS?WSDL',

                                     'uri'      => 'http://DgieWSWeb/DgieWS?WSDL',

                                     'encoding' => 'ISO-8859-1',

                                     'trace'    => 1) );

$respuesta = $client->tiposDeCambioBanxico();

$resp = mungXML($respuesta);

$obj  = SimpleXML_Load_String($resp);

// var_dump($obj);

foreach ($obj->bm_DataSet->bm_Series as $data)

{

    if($data['IDSERIE']=='SF43718'){

            echo $data->bm_Obs['OBS_VALUE'];

    }

}

function mungXML($xml)

{

    $obj = SimpleXML_Load_String($xml);

    if ($obj === FALSE) return $xml;

    $nss = $obj->getNamespaces(TRUE);

    if (empty($nss)) return $xml;

    $nsm = array_keys($nss);

    foreach ($nsm as $key)

    {

        $rgx

            = '#'               // REGEX DELIMITER

            . '('               // GROUP PATTERN 1

            . '\<'              // LOCATE A LEFT WICKET

            . '/?'              // MAYBE FOLLOWED BY A SLASH

            . preg_quote($key)  // THE NAMESPACE

            . ')'               // END GROUP PATTERN

            . '('               // GROUP PATTERN 2

            . ':{1}'            // A COLON (EXACTLY ONE)

            . ')'               // END GROUP PATTERN

            . '#'               // REGEX DELIMITER

            ;

        $rep

            = '$1'          // BACKREFERENCE TO GROUP 1

            . '_'           // LITERAL UNDERSCORE IN PLACE OF GROUP 2

            ;

        $xml =  preg_replace($rgx, $rep, $xml);

    }

    return $xml;

}

?>