Advice for 2-3 month rentals?


I´m looking to rent for a couple of months, perhaps more if I find work. Does anybody have any advice on how to find such a place. I have looked in several places for several days (Clarin Classifieds, BA Herald, Soloduenos,, etc.) but am having trouble finding short term rentals for under $us500/month (or any short term at all so far).
At the moment I´m with a friend, but need to find my own place by the end of the month.

Thanks. Jorge