Ask your doctor. Often they will have swabs and often as not, they'll just give you some.

Just did a Google search for the small vials. This is what came up just in a quickie:

http://www.metromedicalonline.com/03091e.html
http://cgi.ebay.com/Mastisol-Individual-Vials-2-3-ml-Vials_W0QQitemZ9527420517QQcmdZViewItem