I want to travel to brazil and aregentina this summer. Do you know any economial airlines and hotels?

http://4starsouthamerica.com/
http://www.traveldm.com/sites/argentinaspecialist.com/
http://www.flycheapabroad.com/Special-BUF-EZE.aspx?utm_source=cheap&utm_medium=prem&utm_camp aign=chippEZE

http://www.kayak.com/

If you have the time, see here below some interesting itineraries through South-America.

Also, as a foreigner/tourist you are entitled to book with either:
Visit Argentina (Aerolineas Arhentinas) and/or Visit Brasil (Varig) with flight coupons