Ebay offers Waterpik Cordless Revive Water Flosser for $19.98 (reg. $42.49) free shipping.

Product Description:
•Cordless Waterpik water flosser with water pressure control system to adjust water intensity
•Fun colors that look great in your bathroom
•Removes up to 99.9% of plaque from treated areas
•Includes 3 AA batteries, so it's ready to use right out of the box - no outlets or charging needed
•Suitable for use with braces, crowns, bridges, and dental implants
•Waterproof and may be used in the shower
•Perfect for travel and small bathrooms
•Portable and lightweight