http://fischerauktionen.ch has a complete 15th century harness from Nuremberg for sale in an auction in early September. Few pieces are not original though, still the auction starts at 100'000 Euros. I am sure Tobi is going to buy it, so please coordinate your bets with him.
The catalogue brings a few other nice items, like original chain mail, a ceremonial helmet for heraldic displays made from leather, plaster and rope (!) and more original medieval helmets...
http://fischerauktionen.ch/auktionen/399/kataloga.pdf