You may have heard about the Japanese magazine Science for Adults (Otonanokagaku), which recently came with a $30 analog synth kit. I'm now completely in love with the magazine, whose Japanese only website is full of wonders. There's a great little pipe organ - be sure to watch the video at the bottom of the page. The magazine itself looks great - page after page of stuff about organs, waveforms, and building the kit (you can even download extra punch cards). Admittedly it's not quite as elegant as this all-paper pipe organ, but it looks a bit more practical.
Gakken, their parent company, also produce many other great things, including these awesome electronics kits, which look like EMS synths.
(Thanks, Paul)
Posted by Tom Whitwell.
The SX-150 looks to me very much like a PAiA (http://www.paia.com) Gnome (http://www.synthmuseum.com/paia/paignome01.html) with a few bits missing, perhaps.
I picked 2 of these up the day it came out (Thursday), and built one right away. It was quite easy and it's a lot of fun. Sure, it's a little cheezy and very much toy-like, for about $33, it's very much worth it.