You can use output buffering to capture your php scripts output before it is sent to the browser, then store the output in a html file. Then change the links on your website to point to the html files instead of the php files. With some more coding, you can create one php script that will create cache files of your entire web directory. Of course this is all dependent on whether or not you host allows output buffering, and at what byte size.
Use the following code as a guide.
<?
ob_start(); //starts output buffering
include( $path_to_php_script ); // when a php script is included, it is first executed, so the include function returns the html output of the php file
$html = ob_get_contents(); // gets the contents of the output buffer, which is your html, and stores them in $html
ob_end_clean(); // ends output buffering, and does not output the buffer to browser
$new_cache = fopen( $path_to_html_file, "w" ); // will create a new file, or open and overwrite it if it already exists
flock( $new_cache, LOCK_EX ); // locks file to prevent errors when writing
fwrite( $new_cache, $html ); // writes html from $html to file
flock( $new_cache, LOCK_UN ); // unlocks file
fclose( $new_cache ); // closes file
?>
