Bestbuy offers Greenworks - 80 Volt 21-Inch Self-Propelled Lawn Mower (1 x 4.0Ah Battery and 1 x Charger) - Green for $399 (orig. $579.99) with free shipping.

Product Description:
Quickly mow up to 1/2 acre on a single charge, then fully recharge batteries in just 60 minutes. This lightweight, quiet-running self-propelled, rear-wheel-drive mower has variable speed control for mowing at comfortable speeds; SmartCut Technology that constantly monitors grass conditions, then automatically adapts to provide the perfect amount of power needed to get the job done; cutting blades that won’t bog down in tall, wet, or thick grass. Greenworks exclusive Intelligent Power provides constant, fade-free power with no dangerous emissions; and combines Brushless motor technology, lithium-ion battery power, superior cutting, and ultra-fast control systems for powerful output. Includes 4.0 Ah battery and rapid charger. Battery is compatible with 75+ Greenworks 80V products. Life. Powered. By Greenworks. 

• Coverage
  Cuts up to 1/2 acre on a single charge
• Runtime
  Up to 45 minutes of runtime a single charge
• Charge time
  Recharges in 60 minutes
• Constant blade speed:
  3200 RPM
• Performance
  SmartCut Technology constantly monitors grass conditions, then automatically adapts to provide the perfect amount of power needed to get the job done
• Drive system
  Self-propelled, rear-wheel-drive with variable speed control for effortless mowing
• Cutting height
  Seven-position, single-lever cutting height adjustment for cuts from 1.3” to 4.0”
• Cutting deck
  21” heavy-duty steel cutting deck provides maximum airflow for excellent cuts; 4-in-1 design for mulching, side discharge, or bagging, with turbo button for added lift when picking up or mowing through leaves
• Storage
  EZ Fold aluminum handles; just pull, fold, and store vertically in seconds
• Push-button start
  Hassle-free starts with no priming, no choke, and no pull cord
• Visibility
  High Intensity LED headlights for mowing at dawn or dusk
• Traction
  10” rear tires and 8” front tires provide excellent traction on any terrain
• Batteries & chargers
  80V 4.0 Ah battery and rapid charger
• Warranties
  3-year tool and 3-year battery warranties
• Compatibility
  Batteries power 75+ 80V Greenworks products