Best Buy offers the FitBit One Wireless Activity + Sleep Tracker in Black, model no. FB103BK, for $79.99 with free 2-day shipping. (Amazon charges the same, but not with the faster shipping unless you're a Prime member.) That's 20% off, the lowest total price we could find by $10, and the best price we've seen in two weeks. (It was $10 less then but with much slower shipping.) One of the original wearable activity trackers, the FitBit One tracks calories burned, steps taken, distance walked, and stairs climbed. It also tracks sleep, and it feeds all of that data into your smartphone or laptop via Bluetooth.