Airbnb, or look into compartodepto.com for shared apts. For reliability airbnb is the best...!
you may work out a deal with a private owner? www. soloduenos.com.....? from abroad? no Spanish?
Choose a flat along the Santa Fe Av, Corridor for subway and buses.
(One or two blocks on either side),of Santa Fe
Between Callao Av. and Pueyrredon Av.
Figure US$ 500 min. for a studio all inclusive ? (Cable, wifi, water, electric, gas, rent, homeowners fees). 3 months rent upfront to move in...!
Rent a room at a hostel for 2 weeks to figure out where you like to LIVE...
suggest Petite Hostel , Junin ave , Recoleta
http://www.petitrecoleta.com/