Don't know anything about Buenos Aires, but I do know one thing. When it comes to your eyes, you don't look for bargains. There have been problems with some of the lasik "mills", where peoples' eyesight have been destroyed.
What you want is to find a good ophthalmologist who has done a lot of this kind of surgery. Check with some of the bigger hospitals in the city. (especially ones that are "teaching" hospitals) When you meet with the doctor, ask him straight out how much experience he has with this procedure. And follow your gut instincts.