无法用PHP解析pre的文本

I am unable to parse the text in the link using my php. It gives the error trying to get the property of a non-object. anyone know what's wrong?

$html = file_get_html('http://steamcommunity.com/market/priceoverview/?country=US&currency=1&appid=730&market_hash_name=AK-47%20|%20Aquamarine%20Revenge%20%28Battle-Scarred%29');
$ret = $html->find('pre',0)->plaintext;
echo $ret;

The response from the URL doesn't actually have a <pre> - it's straight json.

Your browser puts the content inside a <pre> to make it display properly to you, but that information doesn't actually come form the URL.

e: To make this more useful...

$ret = file_get_contents('http://steamcommunity.com/market/priceoverview/?country=US&currency=1&appid=730&market_hash_name=AK-47%20|%20Aquamarine%20Revenge%20%28Battle-Scarred%29');
echo $ret;

Then if you want to actually use the returned data...

$json = json_decode($ret);