Post in one of the "for trade" threads in the various subforums here. I'm sure someone will have one of those that they can offer. I'll check my own parts bin later, but I think the cantis I have are of a different design that won't have that part.

On the water bottle cage, if it is an aluminum cage, you can just bend it slightly. I have several Camelbak bottles and the they fit all my cages, though the shape does not lock in as tightly as I would prefer on some of them.