Couple of thoughts...
Recently there was a thread on a company that trans-ships to Canada, seems like Dan In Van gave them a try with success.
Next, if i'm looking at the right part of the diagram, part C-10 is an M-8 left hand thread on one end that screws into the plunge base. The other end is tapped as 6-32 for a screw (part C-12) to hold the lever in place. The lever (C-11) would look awesome as a hand-tooled piece of black walnut. Just thinking that if the US source is going to cost $40 +/- in either currency, might be worth a trip to a local hardware to go through the bins!!
Of course, i bet somebody in the lower 48 would be willing to send you a "birthday gift" if we run out of other options!! Eh-eh, nudge-nudge, nod is as good as a wink to a blind horse....(old Monty Python, for those few who might not know!!)