I've noticed a lot of people posting here asking where they can get a large variety of spices from. I've been going to a shop whose entrance is just outside of the main entrance of the Main Building of the Retiro Train Station. They sell spices "a granel" in other words in bulk and will fraction the amount you want (minimum 100gr).

They also have dry beans, rice, and other such commodities that cost 2x as much en el Barrio Chino en Belgrano.

If you are standing in front of Retiro in the Plaza where the Clock Tower is, the entrance to this shop is about 25 meters on your right hand side.

Hope all of you expats looking to enhance your cooking find this useful.