Check it out:
13 NOV 87
Not the oldest, but still fairly old. Whoever asked the question was pretty knowledgeable. I'd say it's at a good price for a "normal" model M now, but given the date, I'd expect it to go up, at least a little.
And an "alt" keycap would be pretty easy to get via unicomp.
(Also, it's pretty easy to get people to forward things internationally. I have done so in the past, though it's generally somewhat expensive, as you can't use first class mail for a model M)