In my opinion, this is yet another example of a neglected Latin American back-of-book issue. Even in the highly unlikely event that every one of the sets issued still remains, it is still grossly undervalued.
This small nation of 4 1/2 million people is unique as the only Latin American country to have escaped the plague of repressive dictatorships and oligarchies endemic to the region. Costa Rica has generally enjoyed greater peace and more consistent political stability than many of its fellow Latin American nations. The government offers generous tax exemptions to those investing in the country,and in recent times electronics, pharmaceuticals, financial outsourcing, software development, and eco-tourism have become the prime industries in Costa Rica's economy. High levels of education among its residents make the country an attractive investing location. Annual GDP growth has averaged 5.6% over the last 5 years.
I have begun a new blog, "The Stamp Specialist", which will feature my buy prices for stamps which I am interested in purchasing. I've just posted a buy list for Costa Rica, including the set recommended in this article. Viewing dealers' buy lists every now and then is an excellent way to keep current on the vagaries of the stamp market.