Awesome! I have been to Argentina, Brazil and have lived 4 years in Chile and now 2 years in Venezuela.
You will love south america but DO NOT bring reps. Customs love reps (to keep/steal). Confiscation of reps does not happen in Venezuela for example, but stealing is not a problem for customs not to mention street gangs, etc.
In Chile, reps are illegal. They are confiscated easily by customs as the people who work at the airports are specifically instructed at training courses to watch out for: drugs, plant products, meat products, dairy products, ammunition, explosives and valuables (they like the one rolex per person law).
Anyway, just get a cheap watch, during your sight seeings I'm sure you'll want a beater.
Enjoy