Try just using:
<?php
$ListItems = new WA_MySQLi_RS("ListItems",$blankcanvas,0);
$ListItems->setQuery("SELECT products.artist_id, products.active, products.sold, products.media_id, products.item_number, products.item_name, products.item_description, products.item_size, products.item_price, products.main_photo, products.detail_photo_1, products.detail_photo_2, products.detail_photo_3, products.detail_photo_4, media.media_name FROM products INNER JOIN media ON products.media_id = media.media_id WHERE products.artist_id = ? OR -1 = ? ORDER BY products.item_name ASC");
$ListItems->bindParam("i", "".(isset($_SESSION['artist_selected'])?$_SESSION['artist_selected']:"") ."", "-1"); //WAQB_Param1
$ListItems->bindParam("i", "".(isset($_SESSION['artist_selected'])?$_SESSION['artist_selected']:"") ."", "-1"); //WAQB_Param2
$ListItems->execute();
?>