Actively Used and Developed Motion Capture Systems
We used the NaturalPoint OptiTrack S250e at my company for a big project that is still in active use today. We used it for a sort of game like exhibition on fairs. So it had to be quite robust and offer stable tracking in changing environments.

It is primarily used for movies and video games though. They offer quite a few different systems in price ranges far below your 40.000$ and far above that, depending on how many cameras you need and what precision you need. The prices are per camera.
They have a nice system configurator here, which makes choosing camera count and camera system a bit easier.

Some of their bigger customers can be found here. Seems like they have been proven in many bigger productions.

I have not affiliation with NaturalPoint and it's the only MotionTracking system I had contact with. There might be better solutions that I don't know of but we used their products and the result were satisfying for our special requirements.