We've found that travel agencies just can't compete with the
discount ticket websites. You can search Google ("cheap airfare
Europe", for example), or go straight to one of the well-known
sites, like Expedia, Travelocity, Cheap Tickets, Hotwire or
Priceline.
Doing a quick search for the cheapest airfare from Tucson,
Arizona, to Buenos Aires, Argentina, using the five sites
mentioned, here's what I just found: They ranged from $1221 down
to $873 for the lowest fares, with fares as high as $3728.
Hotwire happened to be the cheapest, but they were the worst of
the five when I searched for a domestic flight earlier. You
cannot say which service will find the cheapest international
airfare from week to week. My number one money-saving tip is to
always check several websites when shopping for inexpensive
flights.