Easy24h via eBay offers this open-box Bluetooth U8 Smartwatch for Android in Black for $19.98 with free shipping. That's tied with our mention from six days ago as the lowest total price we've seen for a Bluetooth smartwatch. (It's a current low for a similar model by $2.) It features a silicone band, 1.44" touchscreen display, rechargeable battery, and Bluetooth 3.0.
Note: Allow up to three to five weeks for delivery. Also, this watch is also compatible with iOS but some functions may be limited.