As one of its daily deals, Best Buy via eBay offers the Waterpik Ultra Water Flosser in Black, model no. WP-112, or White, model no. WP100W, for $44.99. This $5 mail-in rebate drops it to $39.99. With free shipping, that's $5 below our September mention and the lowest total price we could find by $5. It features 10 settings, 90-oz. reservoir, and six water flosser tips. Deal ends today.