Which airline has the cheapest flights from Central to South America?

I am looking for a flight FROM either San Jose, Costa Rica or Panama City, Panama TO Santiago, Chile. Which ailines offer the best rates from Central America to South America. I am looking to buy a one-way ticket leaving on Jan 6th 2008. I just want the cheapest flight...accomodations are not important to me. Thanks for your help.

Check travelocity and expedia. They will compare airlines for you.

the lowest rates should be on this website http://www.LouMarTravel.com Copa - Compania Panamena is the cheapest Airline followed by TACA

Try Kayak.com, it will search all of the airline and travel websites, always providing the lowest fares. I have used kayak on multiple occasions and it is excellent. Be sure to double check on the airline websites, just to be sure that the one listed on Kayak is the lowest.

COPA or TACA
Now, if you live in USA, you cannot buy these tickets on line, but a travel agency can. (security reasons and fraud)

Did you consider contacting a travel agent? They get paid to find out those things for you.