I too think they would do well here. Furniture prices have really soared in the last few years. I suspect import taxes are a problem for IKEA plus the general difficulty of doing business in an unstable country like this.
I bought a crib from anfarsrl.com.ar Actually got it off mercadolibre, but their site shows all the range. Cheap and not bad in terms of safety compared to a lot of the fancy but dangerous stuff on the market.
Labour and antiques are well priced here, so you can get great stuff built, restored, and you can snap up bargain antiques. There's some great pieces in mercado de pulgas and the surrounding area.
I've picked up amazing 60s design pieces, beautifully restored for the same price as a self assembly piece of junk that Easy are selling. Really depends what you need, but I'd go with a combination of restored antiques and skilled labour to build what you want. You'll get the best value and the best quality that way. Might be more than Ikea, but its money well spent.
Also try SODIMAC home center www.sodimac.com.ar, I bought some great quality ready to assemble furniture there, some I even saw in Buenos Aires Design for double and triple the price. There are several locations, they are huge warehouse - home depot type stores with great garden centers also. They are all in Gran Buenos Aires, zona oeste y zona sur, I recommend going during the daytime only.