You'd probably want Nitto B123 or B125 bars. They come as narrow as 36cm and are available from a whole ream of places, most of which are listed in the LBS/OBS sticky thread. Try Trackstar, Bussiness Cycles, World Class Cycles, or Yellow Jersey for starters. You can also just type "nitto" into the search function on eBay and you'll probably get a lot of hits.
m.