Cheap Headtracking Solution. Download and install Opentrack and then go by your local Radioshack or electronics store and pick up 3 infrared LEDs (if they aren't wide angle you can file them down), a battery holder for 2 triple A batteries, a soldering iron and some solder, 3 15 OHMS resistors, and some jumper pin wiring you'd use in a computer. Go online and buy a PS3 eye and make sure you have an old floppy or exposed film negative to put an IR filter in it. Then look on the Freetrack website for how to make the tracking clip and for how to modify the PS3 Eye to only see infrared light. I think it ran me around $40 for all of that since I did not own a soldering iron beforehand. Otherwise it would have been about $25 - $30. The PS3 Eye is super cheap on Amazon. Ordering the electronic stuff for the clip online would probably be cheaper but I was impatient and wanted it that day.
It was cool for awhile but ate through batteries and the mount for the LEDs was cardboard and got bent eventually as it was hot glued to my headset. Velcro works okay too for keeping it attached to your headset/headphones. Also don't waste your time with Freetrack. The tracking is way too juddery. Opentrack using Advanced Freetrack Protocol for some reason is much smoother than Freetrack itself.
Having gone the headtracking route until I recently got my DK2 I'd have to say that if you can afford the DK2 the headtracking solutions really don't hold a candle to it. The head movements are so much more natural with a DK2 not to mention the depth and scale benefits. The real difference is between looking at a screen of a cockpit while slightly adjusting your head to look different directions and being inside the cockpit looking out the glass. You can even spin around in your chair and look at the back of the cockpit.
