The Events Calendar - Open Price module

openprice.php

<?php
//Add this in your functions.php file
    
    add_action( 'tribe_events_cost_table', 'event_backend_open_price', 9 );
    add_action( 'tribe_events_event_save', 'event_save_open_price', 10, 3 );
    add_filter( 'tribe_get_cost','event_get_open_price',10,3);
        
    function event_backend_open_price($event_id){
        $isOpenPrice = ($event_id) ? get_post_meta( $event_id, '_EventOpenPrice', true ) : false;
        ?>
        <tr>
            <td><?php esc_html_e( 'Open Price:', 'labokube' ); ?></td>
            <td>
                <input
                    tabindex="<?php tribe_events_tab_index(); ?>"
                    type="checkbox"
                    id="openPriceCheckbox"
                    name="EventOpenPrice"
                    value="1"
                    <?php checked( $isOpenPrice ); ?>
                />
            </td>
        </tr>
			<tr>
				<td></td>
				<td>
					<small><?php echo esc_html__( 'Use the price field above as a suggested price.', 'labokube' ); ?></small>
				</td>
			</tr>
        <?php
    }
    
    function event_save_open_price($event_id, $data, $event){
        $isOpenPrice = isset($_POST['EventOpenPrice']);
        
        if ($isOpenPrice){
            update_post_meta($event_id,'_EventOpenPrice',true);
        }else{
            delete_post_meta($event_id,'_EventOpenPrice');
        }
    }
    
    function event_get_open_price($cost, $event_id, $with_currency_symbol){
        $isOpenPrice = get_post_meta( $event_id, '_EventOpenPrice', true );
        if ($isOpenPrice){

            if ( $cost == esc_html__( 'Free', 'the-events-calendar' ) ) $cost = null; //free
            
            if ($cost){
                $suggested_txt = sprintf( '<small>' . __("suggested: %s","labokube") . '</small>',$cost );
                $cost = sprintf(__("Open Price - %s","labokube"),$suggested_txt);
            }else{
                $cost = __("Open Price","labokube");
            }
            
            
        }
        return $cost;
    }