Something a bit unusual, a French Flageolet, probably 19th century, on Ebay at:
http://www.ebay.com/itm/RARE-Early-Flageolet-/110994080787?pt=LH_DefaultDomain_0&hash=item19d7c34413
The pictures don’t tell the full story. The four fingerholes are augmented by 2 thumbholes on the back; the keys provide the accidental notes. There should be a windcap and a mouth tube, although you can just blow into the slot at the top. Making a windcap and mouth tube is not difficult and does make the instrument more comfortable to play. Mouth tubes were often ivory, but I’ve used artificial ivory successfully.
There’s plenty of information on the web about French flageolets, including images, history and fingering charts. I’m not associated with the owner (although she has been in touch to find out what it was!). I’ve mentioned it over on the Whistle list as well.
Terry