I recently led a number of iPad workshops called iPad Academy: Presenting with Your iPad for university faculty. One of the items we used were iHome iHM79 Rechargeable Portable Speakers. We were impressed with the sound from such a small pair of speakers. These speakers can be charged using the USB port on your computer. Tip: you can also recharge then with any iPod or iPhone charger. Just found them at a good price. $19.95 plus $2.00 shipping. These are bulk packaged (poly bag) rather than typical retail plastic pack. Here’s the link.
Tip 2: Do a quick search for coupons at sites such as CouponCabin for possible additional savings before placing your online orders.