Walmart offers the GE Z-Wave Plus Outdoor Remote Control Outlet in Black for $31.99. Opt for in-store pickup to dodge the $5.99 shipping fee. (Amazon charges the same price with free shipping, as does Home Depot via pickup.) That's the lowest price we could find by $13. It is weather- and impact-resistant, and works with SmartThings and other Z-wave certified hubs.

Update: The price has increased at Walmart and Amazon; however, Home Depot still offers it for the same price with in-store pickup.