iStar said:
You can look up the price of medication sold here in Argentina on this site:
http://www.kairosweb.com.ar/default.asp
iStar has the key - Kairosweb is the online version of the system used by the farmacias. If the drug is listed there, it's available.
Almost everything available in the US or the EU is available here. In fact, the Argentine list of medications is about 3 times the size of the equivalent list in the US, where the creators of many valuable medications don't find it worth the cost/effort to register with the FDA.
If you stick to generic versions, retail prices are seldom more than your co-pay would be in the US. At least here in Palermo, most of the independent farmacias offer a discount of about 20% for purchases in cash, and many of these advertise that offer in the window or at the cajero.
In my experience, you can buy almost any prescription medication without presenting any doctor's prescription. Exceptions are psycho-active drugs and certain medications like seudoefedrina ("sudafed") that can be used to create illegal drugs (like crystal meth). For these, the farmacias by law require 2 individual, hand-written copies of the prescription.
That said, a pharmacist who knows you well may provide small amounts of even the highly-controlled medications without a prescription. Some months ago, when a case of hiccups lasted through the night, I remembered a similar event in the US when my doctor there prescribed a low dose of Thorazine, an old drug that was used to treat schizophrenia. I went to my neighborhood farmacia as soon as it opened and explained - or rather demonstrated - my situation, and they bent the rules and sold me what I needed, after explaining that they shouldn't do it, but in emergencies and for people they know well . . . .
For some reason, Farmacity and a few other stores I've tried require prescriptions for what seems to be a random list of other medications. When one store tells me "no," I just go down the street to the next farmacia, where the answer will be "yes."