I think there are several reasons Nitto's stuff isn't widely distributed. One is price, the yen to dollar exchange makes importing Japanese products expensive. Secondly, Nitto is a pretty small company. I think they have 38 empolyees, so they're probably not producing too much product. Lastly, they produce items which don't cater to large market trends. Think about it--quill stems, moustache bars, track drops, high-end racks. As much as we around here admire and use the stuff, we're the minority.
The technomic stem, "regular" road drops, track drops, and moustache bar are all distributed by Quality Bicycle Products, which any lbs should be able to order from.
If you do a little looking around, Nitto products shouldn't be hard to come by. Besides the suppliers alreadhy mentioned, try
http://www.tullios.com/Nitto.htm
--AK