I've been anxiously watching the OptiTrack developments for the past year and a half. Here is a video/interview I recently found showing the system:

http://on10.net/Blogs/laura/optitrack-offers-you-motion-capturing-you-can-do-at-home-and-affordable/

The x factor in my mind is how much cleanup there will need to be of the files. You can see in their live demo that there is some noise (note the legs going wonky now and again). It's hard to say how much time this would save somebody to use if the cleanup is extensive. Most bvh I've encountered--both found and purchased--is usually pretty noisy, so it leads me to believe that the cleanup is the hardest part of mocap.

That said--and taking a page from ed111's idea of a shared community--if , say, somebody working on a specific non-commercial project purchased such a system and generated raw bvh files they created for their project that they then made available to such a community with the idea that individuals might then download a file, clean it up, and return it to the shared space, that might be one way to harness the power of many individuals for the benefit of the community, while also benefitting the purchaser of the system for making the files available.  Just a thought...