LightInTheBox offers the Cop Rose x4 Smart Window Cleaning Robot for $169.99. Coupon code "LCSRB40" cuts that to $126.99. With $6.31 for shipping, that's the lowest price we could find by $36. This device sticks to the inside or outside of your windows, recognizes window borders, and self-plans a cleaning route.
Note: This item ships from China via express expedited delivery and should arrive in two to three business days. Uncheck "Add Shipping Insurance to your order" during checkout to remove the $2.99 fee.