hi, people, I'm a local, and I'm really ready to help you with your question any time I can, I've been trip adviser for years in Lonely Planet forum.
as far it seems that it's not forbidden to talk about my property, I'll tell you also that I'm owner of a flat located in Monserrat (also called Congreso, and some parts taken as San Telmo). I use to define it as cozy, stylish and budget. At this time it has not internet connection, because I received just travellers not people working, if I had a guest who really needed it, I'd add the connection.
oh well, you can see it here
www.photoblog.com/quimera
price is 570 dollars a month, with a refundable deposit as warranty, acording to the stay.
and I have it also in ByT agency, I saw you mentioned. To have an idea why is better to contact directly the owner, I put here the link to my flat in ByT, you'll see the prices are higher and still have to pay fees...
another difference is that I love my city, my flat, and really want people to enjoy their stay, and guests realize of that
And please, if talking about this is forbidden, moderator, please erase it. You'll find my ads in craigslist.
http://bytargentina.com/re/propview.php?view=2883&bookit=&dia_ing=&mes_ing=&ano_ing=&dia_sal=&mes_sal=&ano_sal=