Just to follow up on this thread, I ended up going to the Point Centro de Podología (
http://www.centrodepodologia.com.ar/) across from the Italian Hospital. I initially sent an email request (in Spanish) from their contact page that was ignored, but when I found the time to go in person, they were incredibly friendly and accommodating (in spite of my very limited Spanish). I only waited 20 minutes to get in and get fitted.
They have very modern equipment, and I was in and out in 10 minutes. If you speak very little Spanish, I would recommend taking someone with you who can translate... but I managed nonetheless. Two days later my orthotics (plantillas) were ready for pick-up. I picked them up today, and they came with surprisingly detailed analyses of my walk, stress points, etc., computer-generated and in full colour, no less. The entire cost for this was only AR$420 (C$105). The last time I got orthotics in Canada my
deductible was C$300, so this was an amazing deal!
The clinic is modern, clean and helpful, and the orthotics fit like they're part of my feet. Highly recommended.
Thanks to Roxana and all the others who responded.