I think you can number them, but you would have to manually input sales for each one. Can't think of any other way to do it. Sorry http://www.neopets.com/browseshop.phtml?owner=atlantissix

Add an extra number or word to all of those in your database and make sure to price every single piece different. After you pasted your sales, the price it sold for will tell you which piece sold, just add the extra number or word for that piece in the already pasted sales before submitting and you'll be fine.