if you want to save the actual code of the page then you could do:
$contents = file_get_contents ('/path/to/file.php');
if you want to save the parsed output of a file then you could do:
ob_start ();
include ('/path/to/file.php');
$contents = ob_get_contents ();
ob_end_clean ();
in both cases you will have a variable called $contents, one will be the raw code and the other will be the code after being parsed.