What to think of making your own headtracking device? For less than 10 dollars and a few hours of work you have one system.
The only thing you need are a webcam(a cheap one will do), 3 LED's, some wires and that's basically it.
Just search for Freetrack on the internet and they provide you with all ins and outs.
I am not computer savvy and not a technician (on the contrary) and was able to make my own one. Still very happy with it.
Look if there's a "Simware" shop near you, they are specialised in (like their name sais) simulation ware. If there isn't, you can order online at www.Simw.com.
Another interesting site, more into aviation in general but with a pretty well simulation assortiment is pilotshop.co.uk, here's the link to their headtracking devices: http://www.flightstore.co.uk/simulation/headtracking/
If you can't find a shop near you, order online, I have done so at both in the past and I had reasonable quick deliveries.
like lejo said: yeah...its called freetrack. just built and set mine up the other day. totally worth it. $40 all in all instead of $150 and it does the exact same thing.