Originals are a little hard to find and fairly expensive. Many of the originals had the brass handle removed and sold for scrap many years ago by one of the surplus dealers. Some of these have since had a reproduction brass handle replaced.

Here is one currently on Gunbroker that may have the original handle:
http://www.gunbroker.com/Auction/Vie...Item=124108175

Here is a link to a current reproduction that says they are using the original blade:
U.S. Naval M-1870 Brass Hilted Bayonet (Yataghan): Half Original - International Military Antiques