Most of the sets were probably used as postage and discarded, as Uruguay's economy was in crippled by the worldwide Depression of the '30s, and the only Uruguayans who could afford to collect its stamps were to be found among members of the oligarchy.
With a population of about 3 1/2 million people, most of whom are of European or mixed descent, Uruguay has a stamp collecting population which will probably approach European levels in the years to come. Uruguay is one of the most economically developed, politically stable and least corrupt countries in Latin America, and is moving away from its dependence on agricultural exports and toward development of commercial technologies, especially software. Annual GDP growth has averaged a little over 3% over the last 5 years.
I have begun a new blog, "The Stamp Specialist", which will feature wholesale buy prices for stamps which I am interested in purchasing. It includes a buy list for Uruguay, and includes 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.