Personally I would avoid staying on Florida, too busy during the day, too much noise and to many toutes trying to lure you into the stores. I would suggest the Recoleta Guest House on Laprida http://www.recoletaguesthouse.com/indexengl.htm it is about $50 US a night but is much nicer and in a very good neighborhood. A fun place to stay is Che Lulu in Palermo SoHo, pretty darn cheap and good area too
http://www.chelulu.com/index2.php?idiom=i

Have fun

suerte
SAM