US $300 for a safe plug?? Please tell me I read that wrong. I couldn't find the light switch so I can't whine about how much it costs. However, in direct answer to your question: probably not. Although the XBee supports the Zigbee protocol, the HA series devices have additional requirements and it's unlikely you'll be able to directly control anything with an XBee.
But, I would love it if someone out there told me I was wrong, and that we can use an XBee to control these devices.