Free custom filter for Events Calendar Pro Filter Bar

free.php

<?php

/**
 * Free? filter
 *
 * @package	Young_Hackney
 * @since	0.1
 */
class TribeEventsFilter_Free extends TribeEventsFilter {
	public $type = 'checkbox';

	/**
	 * Output the admin form
	 *
	 * @return string
	 */
	public function get_admin_form() {
		$title = $this->get_title_field();
		return $title;
	}

	/**
	 * Populate the filter with values
	 *
	 * @return array
	 */
	protected function get_values() {
		$values = array(
			array(
				'name'		=> __( 'Free' ),
				'value'		=> 1
			)
		);
		return $values;
	}

	/**
	 * Pass through the args for the query
	 */
	protected function setup_query_args() {
		$this->queryArgs = array(
			'meta_query' => array(
				'relation'		=> 'OR',
				array(
					'key'		=> '_EventCost',
					'value'		=> 0,
					'compare'	=> '=',
					'type'		=> 'NUMERIC'
				),
				array(
					'key'		=> '_EventCost',
					'compare'	=> 'NOT EXISTS',
				),
			)
		);
	}

}

// This adds our new filter to the Filterbar options
// Invokes TribeEventsFilter::__construct($name, $slug);
$yh_free = new TribeEventsFilter_Free( 'Free', 'free' );