I keep finding interesting airline flight deals:  Miami to Santiago return.  These flights are usually on lower cost carriers and may or may not have several stops or changes of planes.  You may or may not find these flights listed through the normal travel service companies such as Travelocity. 
I have no information on baggage allowance at this time. 
 
Here are the two best  "bucket shops" listings from  the 8 May 205 Miami Herald:
 
Nuevo Mondo Travel (Miami)  $489
(plus taxes, restrictions apply)
1-800-228-0088
 
The Travel Center (Miami) $469
(plus taxes, restrictions apply)
305-949-6222
 
WOW (Ft. Lauderdale, Fl.) $468
(plus taxes, restrictions apply)
954-437-2100
 
I have not used any of these travel services and this is not a paid ad.  I'm just passing along what I found in today's paper.  
 
The numbers look good and it may or may not be worth giving these companies a call.    Who knows??????? 
 
As I find more, what appears to be, low cost air fares I'll post them.