Staedtler Compass

Check the craft and office supply stores which carry drafting supplies...you'll probably find them there. Or you could do a search on Amazon.com, I do a lot of my shopping there for all sorts of stuff.

This outfit in Canada sell packs of 12 for $16.20, or if you have shouldered needles, $18.20, they are just past half way down the page, below the bow compass on the right;

http://www.smithdrafting.ca/supplies2008ca.htm

If you only want 1 or 2, try contacting some suppliers as opposed to Staedtler & keep in mind that most manufacturers use the same size of needles (Rotring, Helix.......). Google "draughting supplies" to find some suppliers.