How good is your Spanish? From your perspective, what level of proficiency is required to live in Buenos Aires?
My Spanish is good. To live there though, you'll do okay with just basic Spanish. There are lots of tourists and lots of porteños speak some English. In my experience, they really appreciate any effort to speak their language and will work with you to communicate.
I seriously doubt you'll find a company based in Argentina that will pay you enough to live the lifestyle you want (I'm making a pretty big assumption about your lifestyle based on my lifestyle coming from the US). That having been said, there are tons of smart developers there and the community is pretty great. A lot developers seem to focus on outsourced work for other countries, notably the US.
I guess the biggest question is what do you want to do? Are you a web developer? What do you do now?
Congrats on the move... I bet you'll love it there. I did.