First off, let me create some context to this request - I work in a university physics department and we run a programming mini-project aimed at teaching first-year undergraduates about hardware/software interfaces and a basic introduction to electronic control systems. We teach our undergraduates python as a first programming language, so as you may have guessed, we use RaspberryPi/BrickPi for this project. It's really popular and the students (and staff!) have a lot of fun, but we try and encourage them to develop something that has a physics focus. We have one of the Lego magnetic sensors, but it seems pretty unreliable, so I was delighted to come across the dCompass which uses the same Honeywell sensor we use in our research labs for active magnetic field compensation at the milli-Gauss level, which should easily be sensitive enough for a little magnetic-field sensing experiment. Unfortunately this doesn't seem to be on sale any more? Is there a technical reason for this, or just a business decision?
A couple of requests then - (assuming there were no technical reasons why you stopped selling them) is there any chance you could make the PCB schematics and firmware available (either privately or publicly) so we can get a couple made? Or, being slightly cheeky, do you have any old stock left that you could donate for educational purposes?
Keep up the great work