Use this snippet to define your own custom price strings for Composite products, for instance when the "Hide Price" option is checked to reduce server load.

woocommerce-composites-custom-price-html.php

<?php
/**
 * Plugin Name: WooCommerce Composite Products - Custom Composite Price Strings
 * Plugin URI: https://woocommerce.com/products/composite-products/
 * Description: Use this snippet to define your own custom price strings for Composite products, for instance when the "Hide Price" option is checked to reduce server load.
 * Version: 1.0
 * Author: SomewhereWarm
 * Author URI: https://somewherewarm.gr/
 * Developer: Manos Psychogyiopoulos
 *
 * Requires at least: 3.8
 * Tested up to: 5.3
 *
 * Copyright: © 2017-2020 SomewhereWarm SMPC ([email protected]).
 * License: GNU General Public License v3.0
 * License URI: http://www.gnu.org/licenses/gpl-3.0.html
 */
 
// To use this snippet, download this file into your plugins directory and activate it, or copy the code under this line into the functions.php file of your (child) theme.

add_filter( 'woocommerce_get_price_html', 'wc_cp_custom_price_html', 10, 2 );
add_action( 'woocommerce_product_options_general_product_data', 'wc_cp_composite_custom_price_html', 11 );
add_action( 'woocommerce_admin_process_product_object', 'wc_cp_process_custom_composite_price_string' );

function wc_cp_custom_price_html( $price_html, $product ) {
    if ( $product->is_type( 'composite' ) && ( $custom_price_string = $product->get_meta( '_custom_composite_price_html', true ) ) ) {
        $price_html = $custom_price_string;
    }
    return $price_html;
}

function wc_cp_composite_custom_price_html() {
    echo '<div class="options_group show_if_composite">';
        woocommerce_wp_text_input( array( 'id' => '_custom_composite_price_html', 'class' => 'short', 'label' => __( 'Custom Price String', 'woocommerce-composite-products' ), 'description' => __( 'Enter a custom Price String to override the auto-generated Composite product price displayed in the shop.', 'woocommerce-composite-products' ), 'desc_tip' => true ) );
    echo '</div>';
}

function wc_cp_process_custom_composite_price_string( $product ) {
    if ( ! empty( $_POST[ '_custom_composite_price_html' ] ) ) {
        $product->update_meta_data( '_custom_composite_price_html', stripslashes( $_POST[ '_custom_composite_price_html' ] ) );
    } else {
        $product->delete_meta_data( '_custom_composite_price_html' );
    }
}