While I was putting this together, I thought of several things that every classroom should have in their science center. Maybe you could add these to your wishlist. :) First, everyone should have at least one set of eyeloupes (only 3.99 at harbor freight). http://www.harborfreight.com/5-piece-loupe-set-98722.html
They are so much better than the little magnifying glasses that come in most science kits. Each one has a different magnification.
Next, are digital scales. Also at Harbor Freight: http://www.harborfreight.com/1000-gram-digital-scale-97920.html. These are a little more ($11.99), but you will use them! We measure grow creatures, mealworms, other insects, and more.
Finally, microscopes. These are a little more costly, but so worth it!
Have a great week!