An Amazon Auto Links extension plugin of WordPress that drops products if they don't have price information.

amazon-auto-links-prop-products-without-price.php

<?php
/**
 *    Plugin Name:    Amazon Auto Links - Drop Products without Price
 *    Plugin URI:     https://en.michaeluno.jp/amazon-auto-links
 *    Description:    Drops products without a price
 *    Author:         Michael Uno (miunosoft)
 *    Author URI:     https://michaeluno.jp
 *    Version:        1.0.0
 */

/**
 * The loader.
 */
class AmazonAutoLinks_DropProductsWithoutPrice {
    /**
     * Sets up properties and hooks.
     */
    public function __construct() {
        add_filter( 'aal_filter_unit_each_product_with_database_row', array( $this, 'replyToFilterProduct' ), 200 );
    }

    /**
     * @param    array $aProduct
     * @return   array
     * @callback add_filter() aal_filter_unit_each_product_with_database_row
     */
    public function replyToFilterProduct( $aProduct ) {
        if ( empty( $aProduct ) ) {
            return $aProduct;
        }
        if ( empty( $aProduct[ 'formatted_price' ] ) ) {
            return array();
        }
        return $aProduct;
    }
}
new AmazonAutoLinks_DropProductsWithoutPrice;