You want part number KHM2B. It's supposed to work with all KitchenAid hand mixers post 1997. Searching for "KitchenAid KHM2B" on google turns up lots of results, including the official kitchenaid store:
http://www.kitchenaid.com/catalog/product.jsp?src=Hand+Mixer+Accessories&cat=223&prod=453
Shipping tends to be expensive. The best price I found was $17.90 including shipping (via usps) from goodmans.net:
http://www.goodmans.net/item.asp?n=KA%2DKHM2B
Note that goodman's has mixed reviews on resellerratings:
http://www.resellerratings.com/store/Goodman_s
Bryce Allen, December 2007
