What can anyone tell me about them?

From when to when they were made, how rare they are, etc. And, approximated year of that one on the link below ( my guess is 1952 or 1953, or maybe 1951 ).

Initial bid on that one ( converted from Brazilian R$ to US$ is US$ 300,00 - not a bad price for Brazilian standards, considering that early 50's sets are pretty rare here ).

Anyway, I am out of money, so I sent this auction link to a friend of mine. Hope he is interested:

http://produto.mercadolivre.com.br/MLB-75054878-televiso-antiga-de-wald-high-definition-_JM