Yojimbosgarage.com. i just bought 40 spokes from him (36 plus spares). Cut to size and threaded. 20 Sapim "strong" and 20 Sapim "force" for my 35 year old rear wheel. The "strong" are on the DS and the "force" are on the NDS. Made a very nice and robust wheel. Marco was easy to work with and knows his trade.
Oh, yah. All 40 spokes and shipping was only $36 and change.
Jon