Here are two models I found:

http://www.archive3d.net/?a=download&id=9c799b22
http://www.blendswap.com/blends/view/85015

The second one requires Blender to simplify its high vertices count (with Decimate modifier) and convert it to OBJ format. If you like it, just use the model attached to this message (available under CC-BY-NC).