Wal Mart has on clearance the Onn (Wal Mart brand) Presentation Clicker. It is basically a wireless PowerPoint remote. Many places show $3, though some are as low as $1. Not sure I would trust it in a business setting, but for that price worth a shot. Check Brickseek for availability and pricing in your area.
Here is a link to the product at Wal Mart, but remember this deal is in store only.