So I will be coming from California and travelling with LAN Airlines. The flight will make a stop in Chile and then BsAs.
I own a flat in BA so I don't think there should be a problem. However, last time a flew down we stopped in Texas and then went to BA. Not so sure about Chile and Argentina being happy without me providing a return ticket.
I got my one-way ticket for just under $500, flying out of JFK and through Mexico City. The American Airlines check-in agents in New York hassled me a little, but I told them I was going to buy my ticket once I arrived. At customs in Argentina, they didn't even ask about when I planned on going home. If they do ask, just say you plan to buy a ticket once you get to your home address (and say that you plan on leaving within 90 days).