woocommerce-custom-post-type.php

<?php
// WooCommerce into Activities Post Type
// added 'activities' post type here

if(class_exists('WC_Product_Data_Store_CPT')){
    class IE_Activity_Data_Store_CPT extends WC_Product_Data_Store_CPT {

        /**
         * Method to read a product from the database.
         * @param WC_Product
         */

        public function read( &$product ) {

            $product->set_defaults();

            if ( ! $product->get_id() || ! ( $post_object = get_post( $product->get_id() ) ) || ! in_array( $post_object->post_type, array( 'activities', 'product' ) ) ) { //Change activities with the post type 
                throw new Exception( __( 'Invalid product.', 'woocommerce' ) );
            }

            $id = $product->get_id();

            $product->set_props( array(
                'name'              => $post_object->post_title,
                'slug'              => $post_object->post_name,
                'date_created'      => 0 < $post_object->post_date_gmt ? wc_string_to_timestamp( $post_object->post_date_gmt ) : null,
                'date_modified'     => 0 < $post_object->post_modified_gmt ? wc_string_to_timestamp( $post_object->post_modified_gmt ) : null,
                'status'            => $post_object->post_status,
                'description'       => $post_object->post_content,
                'short_description' => $post_object->post_excerpt,
                'parent_id'         => $post_object->post_parent,
                'menu_order'        => $post_object->menu_order,
                'reviews_allowed'   => 'open' === $post_object->comment_status,
            ) );

            $this->read_attributes( $product );
            $this->read_downloads( $product );
            $this->read_visibility( $product );
            $this->read_product_data( $product );
            $this->read_extra_data( $product );
            $product->set_object_read( true );
        }

        /**
         * Get the product type based on product ID.
         *
         * @since 3.0.0
         * @param int $product_id
         * @return bool|string
         */
        public function get_product_type( $product_id ) {
            $post_type = get_post_type( $product_id );
            if ( 'product_variation' === $post_type ) {
                return 'variation';
            } elseif ( in_array( $post_type, array( 'activities', 'product' ) ) ) {  //Change activities with the post type
                $terms = get_the_terms( $product_id, 'product_type' );
                return ! empty( $terms ) ? sanitize_title( current( $terms )->name ) : 'simple';
            } else {
                return false;
            }
        }
    }

    add_filter( 'woocommerce_data_stores', 'ie_woocommerce_data_stores' );

    function ie_woocommerce_data_stores ( $stores ) {      
        $stores['product'] = 'IE_Activity_Data_Store_CPT';
        return $stores;
    }
}

add_filter('woocommerce_product_get_price', 'ie_woocommerce_product_get_price', 10, 2 );
function ie_woocommerce_product_get_price( $price, $product ) {
    if ($product->post->post_type === 'activities'){ //Change activities with the post type
		  $price = get_post_meta($product->id, "starting_from", true);
    }
	return $price;
}