Add price suffix

add_filter( 'woocommerce_get_price_html', 'mx_text_after_price' );

function mx_text_after_price($price){

    $text_to_add_after_price  = '<small> (cijena za gotovinu) </small>'; // tekst po želji

    return $price .   $text_to_add_after_price;

}