Has anyone looked at the Wio family of products made by SeeedStudio? They seem like they would be perfect for OpenHab. http://wiki.seeed.cc/Wio_Node/
Cheap, easy to set up, insanely flexible, a restful API, and a lean Python server option that could probably be replicated as part of a binding.
I’m impressed by one I’ve got with a couple sensors, and have more sensors on the way that I am going to integrate into my OpenHAB system (although I’ll likely use the REST binding instead of making a new one since it should be quicker).