While not a true theremin per se in terms of sound generation and antenna circuitry, the One Theremin Per Child project has a noble mission; it aims to produce a decent quality theremin for under $30. Rather than a traditional approach, the OTPC uses wavetable synthesis to produce its tone.
OTPC appears to be the brainchild of Shawn Wallace of AS220 Labs, a community electronics lab in Providence, RI. It has no relation to the One Laptop Per Child program.
We'll share more as we learn about the OTPC project, including how you can get involved. Kudos to OTPC for World Thereminization!
Thanks to GordonC for finding this and posting it in our forums!
Visit: One Theremin Per Child