maybe you can find an 'intercambio' here:
http://www.mundoanuncio.com.ar/categoria/intercambio_de_idiomas_34.html
or, i would suggest, going to many of the gringo/porteno bars (alot of these bars have a mix:
http://www.whatsupbuenosaires.com/wuba2/index.php?tarea=hotlist&idSet=2 )
and just try to strike up conversations... i met a lot of people who just wanted to to meet gringos and practice english and were willing to do language exchanges.
Intercambios are a great way, its free and youll actually learn a lot by noticing the errors that spanish speaklers make in english.
These teachers are really good!:
http://www.eniedespaniol.com.ar/
whenever i had questions that non-spanish teachers couldnt explain clearly, i would schedule a few seessions with them, now we are good friends. they are very professional and bring you into their community
of other spanish/english learners!
, i posted this earlier, but i was in the same situation, and found an intercambio. i made this website:
http://www.faltamucho.com/
with all my notes, and i continue to add to it to keep me motivated to learn more... hope this helps. suerte!! eric