Originally Posted by
JDiver
The visa fee is a reciprocity fee, pure and simple, charged by Argentina and Brasil (Canadians pay $65, Australians $35 in reciprocity fees). Many South American countries have agreements with the USA now waiving fees (e.g. Chile, which used to have a $160 fee).
The big difference between Brazil and Argentina is that Brazil requires that you either go to a consulate or send your passport off with pictures and forms and can take a while, Argentina is an easy on-line application and payment where you print your own form to take with you.
In my opinion, for a mileage run Santiago is easiest, followed by Buenos Aires.