man tough to find, i think the problem with a mouse like that is most people would be inaccurate with their button pushing.. especially with such a seamless design like that. Not saying you would, but it would be hard to get mass manufactured as most people would probably not like it... I know I use a KONE which is a big mouse, and I still push some of the buttons accidentally.
Hope you find what you're looking for! I searched for a while with no luck. I think there are companies where you can customize mouses, but even those I don't think have that feature.