Mindboards

Both of those sound as though they could be made on the software level. Is there a need for a HW side?

Some of you may be wondering what happened with my air-pressure thing. I have a functional prototype, but it's still way bare-bones, and other things are more important ATM. Sometime in the next couple of months, I should have a video showing basic functionality.

To answer the original question of this thread;

I sold 2 RCX PIR sensors I made on Ebay for about $20 recently. They cost me ~$5-$10 to make each of them and about 2 hrs (first prototypes, hand built). It took me about 3 months to sell them and about 3 reposts.

I have a few layouts to get a batch of PCBs made for a couple different kinds of sensors, but have not pulled the trigger on it yet. Profit margin is still a question, vs time/materials.

So, yes, there appears to be some demand for sensors from those that do not want to build their own, and possibly save $$ compared to officially endorsed 3rd party sensors. The problem is, this would be for a relatively low cost application, so your target sales price is also small, hence your profit margin small. Demand does not appear to be huge, and probably depends on item, presentation and $$.

I have some ideas for different sensors that may be of use, though....so maybe...