They may not be any lighter but Origami Shelves fold up which might make them convenient for portability.  You may find some cheaper or even more compact foldable shelves as well but the Origami shelves are pretty nice.  I've also seen some plans for DIY break down shelves if you want to go that route.  

--Nathan, TX. Hire the lazy man. He may not do as much work but that's because he will find a better way.