Note (9/10/13): This is a work in progress and there are no kits available yet. Please watch this space or email us if you are interested.
Here you can buy a kit of the open-source charge controller. This includes all parts and a pre-programmed microcontroller.
Full instructions for making your kit are available here.
If you build a kit or use the deign at all then please let us know. We would love any feedback. Let us know if you would like to get involved with the project.