Try eBay. You may have to wait a little longer if it's coming from Asia, but the shipping prices are much more reasonable than some US sites. (I ordered 10 for 3.99, and that includes shipping. A domestic site wanted .99 each, plus $7.50 shipping. Go figure.)
Also, be sure you're getting the right length. I noticed 3 different sizes- 10, 20 and 30 mm. For my Garmen car adaptor, I needed the 30mm.
Ken, September 2011