Amazon – Up to 40% Off Select Lawn Mowers (Today Only). As one of its daily deals, Amazon offers Prime members the Greenworks 21″ 40V Brushless Cordless Mower with two 2.5AH Batteries for $245 with free shipping. That’s $2 under our Prime Day mention and the lowest price we’ve seen. (It’s the best price today by $135.) It features Smart Cut technology, which automatically increases the speed of the blade when more power is required.