I've been wanting to start playing around with Zigbee and ran across the Smartenit USB ZigBee HA Coordinator: http://smartenit.com/product/usb-cid/
At a high-level it seems like the Aeon Labs Stick for Z-Wave and is reasonable IMO at only $50USD. It seems like it may be a good device to allow Indigo into the Zigbee world and may offer a path to Zigbee-enabled locks.
Smartenit has several devices already communicating through Zigbee: http://smartenit.com/shop/zigbee/zigbee ... utomation/
EDIT: As another option, they also have a single device that combines and Insteon PLM and a Zigbee controller into one device: http://smartenit.com/product/zbplm/
Terry