Bellybands.net I had a friend that bought one for his Dane from them a couple years back.
Deborah S. replied:
However, they are plentiful on http://www.ezwhelp.com/BuyBellyBands.htm?gclid=CNPHod_F0 boCFTJp7Aodsz4AAA. Lemme know if you need a special one and I will try to help :)