Switch Free prices to "Price upon Request"

price-upon-request.php

<?php
/**
 * Plugin Name: Price Upon Request
 * Plugin URI: https://gist.github.com/helgatheviking/6278f960f5fb7fca101e75f30f33141c
 * Description: Switch Free prices to "Price upon Request"
 * Version: 0.1.0
 * Author: helgatheviking
 * Author URI: https://kathyisawesome.com
 * Requires at least: 4.7
 * Tested up to: 4.7
 *
 * Text Domain: your-plugin
 * Domain Path: /languages/
 *
 */
if ( ! defined( 'ABSPATH' ) ) {
	exit; // Exit if accessed directly.
}



/**
 * Hides the 'Free!' price notice
 * @param bool $price
 * @param WC_Product obj $product
 * return string
 */
function kia_hide_free_price_notice( $price, $product ) {
	if ( $product->get_price() == 0 ) {
		$price = '<span class="woocommerce-Price-amount amount">' . __( 'Price upon request.', 'your-plugin' ) . '</span>';
	}
	return $price;
}
add_filter( 'woocommerce_get_price_html', 'kia_hide_free_price_notice', 10, 2 );

/**
 * Shows the notice for varitions
 * @param bool $show
 * @param WC_Product_Variation obj $variation
 * return bool
 */
function kia_show_variation_price( $show, $variation ) {
	if ( $variation->get_price() == 0 ) {
		$show = true;
	}
	return $show;
}
add_filter( 'woocommerce_show_variation_price', 'kia_show_variation_price', 10, 2 );