As you can see from this dump of the output the currency is missing from the output so we have a blank key should be 'aud'

["rich_snippet"]=>

object(stdClass)#151 (1) {

["top"]=>

object(stdClass)#150 (2) {

["detected_extensions"]=>

object(stdClass)#149 (3) {

["rating"]=>

float(4.9)

["reviews"]=>

int(13)

[""]=>

float(159)

}

["extensions"]=>

array(4) {

[0]=>

string(11) "Rating: 4.9"

[1]=>

string(13) "‎13 reviews"

[2]=>

string(10) "‎$159.00"

[3]=>

string(11) "‎In stock"

}

}

}