If you're working on rhythm with a group of kids--especially if you're using my Rhythm for Kids curriculum--then you might be interested in my collection of slightly used boomwhackers. There are 76 boomwhackers with caps on 50 of them. The caps lower the pitch an octave, and you can remove them or switch them around however you want. Here's how the boomwhackers break down: 15 orange (D), 17 yellow (E), 23 green (G), and 21 purple (A).
With shipping costs being what they are today, I've added my estimate of $35 for shipping to the total cost of this deal. So you get the boomwhackers and the cups plus shipping for $59.95. (Sorry but I can only ship within the U.S.)