I got the CAD200 at Friends Syokai in Asagaya. However, most good bike shops sell them, for instance Y's etc....
Wish I'd got it overseas though and had it shipped in. The price difference is pretty high even including postage and packaging, like in the ichi man + area. Amazon etc in the US don't ship this overseas but I've heard that some of the smaller online shops will.
I also got my CAD200 at PBK... Saved about 1 man or so.
Not too impressed by the Polar computer, btw... It tends to lose the cadence and wheel sensor signals fairly easily, at least 2 or 3 times a ride (Richy152, didn't you have similar experiences?).
If I could do it over, I'd keep the reliable and cheapo Cayeye computer on the bike and just get a wris****ch heartrate monitor. It would be easier to take to the gym (where I need it more) and I could still strap it around the handlebars for time trials and the like.
When I first got it I did have these troubles, basically because the settings are very sensitive (<4mm gap between the sensor and magnet) and my transportation in the rinko bukuro was always upsetting the instruments. Since I got a new bag where I don't have to take the rear wheel off I've had no major problems.
While I'm more than happy with the performance of the computer itself - though I've noticed I sometimes get a deviant heartrate where it's >200bpm (typically on descents strangely), the "sonic transfer" mechanism on the CS200CAD has been useless. I haven't got it to work either on my desktop or my wife's laptop.
If I had to get one again, I would get the same one as Simon (the 400 which I think has the USB transfer) as well as get it overseas, where it's cheaper.