The following Argentina visa (tourist) reciprocity tax apply only if you are a citizen of US, Canada and Australia.
It is the equivalent to what Argentinian tourists have to pay for visiting those countries, hence the name reciprocity.
Up to now, the recirpocity fee was paid on arrival to any Argentina point of entry, however, from January 1st, 2013 it will need to be paid online in advance.
Failing to do so will result in denial of entry.
To sort this matter out, just do the following...
As for December 2012, reciprocity tax will be charged according to the following rates...
In all cases - irrelevant of your country of citizenship - it is recommended to travel with at least six month validity on your passport and to ensure it has enough number of unused pages for reasons of stamps.
To check if you need a tourist vista to enter Argentina, please visit the official page of the Dirección Nacional de Migraciones (page in Spanish). Alternatively, contact your nearest Argentinian Embassy, please find the list of embassies and consulates in the world here.
Most importantly, due to the fact that visa requirements can change anytime, make sure to contact the appropriate embassy or consulate prior to your departure. You can also visit the official page of the foreign ministry of Argentina (page in Spanish).
By having your Argentina visa in place you are guaranteed to have a superb vacation and avoid umpleasant surprises at the point of entry.