I really couldn't speak to the value of such a set - but you are correct in that it's an interesting find!
If it's from the Fifties, than the two USPC decks are in the correct period - for the Ace of Spades coding, S was the letter code for decks made in 1953 and T for 1954. The other possibilities would be 1933/34, which is doubtful considering the materials used to make the card holders, or 1973/74, also doubtful because companies were using ZIP codes in their addresses by then and this doesn't have any that I've spotted.
The Ace of Spades code wasn't used on the pair of "V 3" decks. USPC never issued decks with a "V" for the AoS code because it could be confused for a Roman numeral five, so the decks were a different manufacturer. I'd venture a guess that they might be made by Arrco, as this company shares the same hometown as Arrco did before they were bought up by USPC a few decades later.