As of right now I have 10 bare 4 cell balancing PCBs remaining. If anybody wants to build some themselves, I'll happily sell you the bare boards for cheap ($5 each plus shipping) and share the design data with you (bom, schematic, etc). Warning though, they are all surface mount parts, don't bother trying to solder by hand unless you have a lot of time. I etched my own stencil, applied solder paste, and reflowed the boards myself. Bottom line, it's a pain.
In order to make this more of a true "diy" project, I'm experimenting with a few different ideas. The most promising one right now is using an ATtiny microcontroller to monitor cell voltage, turn the balance resistor on/off, and send an HVC/LVC signal. Component count drops substantially, everything is available in a through hole version, and it's actually less expensive to build than the pure analog version. The added bonus is that since it's microcontroller based, changing the HVC/LVC voltages is as easy as changing 2 variables in the code and re-uploading the firmware, which can all be done using the Arduino IDE (or any other AVR compatible option you prefer).
Thoughts?