Interestingly, their patent quoted on the site suggests that this is really just a SPD modifying filter sandwich on top of halogen lamp.
Yes, the principle has been known for very long time, I haven't read the patent in full so I don't know what's actually new in theirs, but I'm suspecting that the new thing is that the package is small enough so you can just clamp filters directly onto the lamp.
The Spectralight viewing booth use the same technique (but filters are away from the lamps), but liulabs product is the only one I've found where you can buy lamps separate, and 300 bucks is a bargain compared to buying a viewing booth.
The challenge is in designing the filter with a precise response to get a good spectral match. We're paying basically 300 bucks for that filter, I guess the lamp is a standard $3 MR-16.
I've experimented with Solux lamps and standard color balancing filters, and while you easily get 6500K, the spectra is not remotely close to follow a D65 shape.
Halogen can't do UV, so below 400 you don't get much output. For camera profiling this should not be a problem though.
From my experiments the main reason for getting this type of thing would be to profile glossy targets, and for me there's some added value in repeatability when developing the software. Matte targets can be profiled in free outdoor daylight without too much glare issues.