I'm sure it's possible, but I don't really know where to look, or how long you'll have to search before you're eventually successful. You could have him just find one for you... there's nothing saying he HAS TO install it for you. Just pay him for it and do the work yourself. Or maybe there will be one lurking somewhere on Ebay- again, I don't know.
I'm just trying to present you with a more reasonable and (probably) quicker course of action.
I’m after a new mainspring for a vintage Rolex and am in the same boat. So I took it to a watchmaker I have used many times before. He will have to install it so let him go through the hassle of finding it.