The essential ingredient, salted dried codfish, usually comes from Norway (bacalhau da Noruega), Iceland (bacalhau da Islândia) or Newfoundland (bacalhau da Terra Nova). It used to be very affordable, but with the collapse of the cod stocks and dismantling of Portuguese bacalhoeiro fleet, it became more expensive, especially near Christmas time, since it's a part of many traditional dishes of the holiday season.

*Sources- Wikipedia and Hungrymonster.com