60V 21" Cordless Battery Self-Propelled Lawn Mower w/ Two (2) 4.0Ah Batteries & Dual Port Charger From Greenworks.com for $425 after coupon code SPT1XQZL.
Seems better than the Costco deal, $75 cheaper and two 4.0 batteries vs a 4.0 and 2.0. But you will give up the Costco warranty.
https://www.greenworkst