Hildy from Ferretware sells those.  She has lots of great ferret items,
check out her site at http://www.ferretware.com   She has the Ferret on
Board sign and others like Ferrets Crossing.  If you check out the sight
you'll find so many fun and unique fuzzie items!  Hildy was very kind and
has been generous in donating items for the Mass. ferret shelters to use
in their fundraising.  I'm so happy to be able to recommend her!
 
Dooks!
Risa
[Posted in FML issue 4246]