As far as the market, it is definitely much better than pretty much anywhere else these days. I have just sold my house and it took me less than three months (it's a property in the $ 200,000 uSD range, which has never been too easy to sell); a friend of mine sold her Palermo apartment the first weekend she advertized it.
What is true is, a lot of buyers (Argentinians more than expats) stay away from properties listed by real estate agencies for several reasons: first and foremost, extra $ 4000 USD on a $ 100,000 property does not apeal to anyone, but if we speak about higher-end properties, the commission becomes a deal breaker. Second, the general dislike of agencies, more so the parasite real estate agents, who really do not create or contribute to anything and do not do much for the obscene amount of money they charge.
Lots and lots of transactions are completed by owners and the resourses for marketing your property are plentiful: duenovende.com.ar(soloduene.com.ar), enbuenosaires.com. zonaprop.com,ar, Clarin calssifieds, craigslist, etc.
I have sold three properties recently: 2 by myself and one with an agent. I honestly can say that what I paid to the agent (1.5%) I could have saved with a very small investment into a sign on the property.
My best purchase out of the four that I have been into, was also through an owner - and the fastest closing, on more flexible terms.
Most of my friends have followed my example and thanked me for the money they had saved. But, it is certainly a personal decision of everyone based on the level of comfort one has in general.
