LightInTheBox offers the Xiaomi Mi Band 2 Fitness Band in Black for $23.99. Coupon code "OZB105064470A" cuts the price to $19.99. With free shipping, that's tied with our November mention as a $5 low and the best price we've seen. It's compatible with Android and iOS and features calories burned, heart rate monitor, and activity tracker.
Note: This item ships from China and may take two to five weeks to arrive. Uncheck "Add Shipping Insurance to your order" and "Postal Service - Tracking" during checkout to remove the extra fees.