when I went the first time, I hadn't brought the photos, and there are lots of people in the little walkway between migraciones on the way to the subte selling food and taking pictures. they gave me 4 or 5 for $40 or something like that. sure it's a bit shady and possibly dangerous (eh, i didn't think so, but this might be something people respond to say) but there were lots of people walking through that walkway, and i went with someone else. it took 5 minutes, and we just crossed the street again to get back to migraciones.