SX-150 is an analog synthesizer kit that is included in a Japanese magagine "Otona-no Kagaku" (means "Science for Adults"). The magagine is known for its scientific toys included in each issue, such as home planetarium, record player, theremin, etc.
We will have the magagine's special edition "Synthesizer Chronicle" on 30 July 2008. The issue includes an analog synthesizer SX-150. SX-150, in spite of its low price (3360JPY), has components that normal analog synths have, such as VCO, VCF, Envelope Generator, and LFO.
It's not only a toy but you can use it as a "musical instrument".