You can do this the way you are doing it by doing your own php function and target the page you need with
<?php
if ( is_home() ) :
get_sidebar( 'home' );
elseif ( is_portfolio page1() ) :
get_sidebar( 'portfolio page sidebar' );
else :
get_sidebar();
endif;
?>
add more elseif statements for as many page & sidebar combination you will have
or you can download this plugin and use the code above the same way