How do you measure these things? Or to be more specific, what size are the ones on the end of an ambassadeur shaft? Seems like it would be much cheaper to buy a pack of them from a fastener supplier rather than buying them from Abu.
Usually they are spec'ed by shaft size and thickness of the c-clip.
Mcmaster.com will have what you need.
Good luck
This might give some info
http://www.circlip.net/pdf/5.pdf