Actually, taxis in Buenos Aires are really cheap. A week's worth of
taxis won't cost as much as the $160 reciprocity fee that US passport
holders have to pay.
Canadians have to pay USD 92 (which is about CAD 160, so you are still
right, but :)
The reciprocity fee is set to match the cost of the corresponding visa
application. It's USD 160 for US passports, or USD 100 for Canadian or
Australian passports. It's good for one year for Australians, ten years
for Americans and Canadians so don't lose it. You can reprint it from
their web site if you can remember when you applied for it, but it's
easier just to save the PDF and/or printout.
http://cnyor.mrecic.gov.ar/en/content/reciprocity-fee-us-canadian-and-australian-citizens-online-payment
I got mine for a meeting in 2013 so this is the third time I'll use mine.
What a bargain.
R's,
John