According to the Standard Catalog of World Coins, the US Mint produced 11,426 proof sets in 1940 and sold them for $1.89 each. According to the same source, a 1940 proof set is currently valued at US$1,475.00. If you have one, however, I would suggest going to a reputable coin dealer for a better valuation based on the condition of your particular set.
Depends on what kind of a set it is. Official mint set, mint proof set, or just 5 coins someone put in a holder? An unopened (still in sealed official U.S. mint packing envelope) US mint silver proof set sold for $29.98 on Ebay on 10/14/2009.
A 1940 US proof set is rather valuable. As of 02/2015 an estimated retail price is around $1500.
You probably have an annual proof set since an uncirculated annual set was not minted that specific year. Nevertheless, a 1950 annual proof set is worth: $650 - $900.
Those are very common -- worth less than a dollar.
NO US proof sets were made in 1965-1967 but they did make Special Mint Sets the coins in these sets do have some proof like details. Current retail value for a 1965 set is $8.00 issue price was $4.00
With original Mint packaging retail is $30.00 for a Silver Proof Set
The U.S. Mint does not make "proof mint sets" of any year. The two types of sets have very different coins in them. A 1980 PROOF set has a current value of $5.00 and was issued for $10.00. A MINT set has a value of $8.00 and was issued for $9.00.
July 9, 2009 The Uncirculated US Mint set is valued at about $15. The 2005 US Mint Proof set is valued at about $25. The 2005 US Mint Proof set is valued at about $42.
July 9, 2009 The Uncirculated US Mint set is valued at about $15. The 2005 US Mint Proof set is valued at about $25. The 2005 US Mint Proof set is valued at about $42.
The 5 coin proof set has a value of $6, the 10 coin set has a value of $15 and the 10 coin silver set has a value of $48.
Current value of the 2003 10 piece Proof set is $10.00. Issue price was $19.95.
The 2006s 10 coin proof set has a retail value of $31.00 issue price was $16.95
A normal 1991 S proof set is worth $9. A 1991 S proof prestige set is worth $51.
In original box as issued from the Mint retail value is $84.00, issue price was 19.95
There is no record of the Royal Mint having produced a "gold" Proof set in 1974, only the usual Proof set. Royal Mint gold Proof sets issued from 1980 contain only the "Sovereign" coinage.
Proof sets were not made in 1965, but a 1965 special mint set is worth $12.00 USD.
8 to 12 dollars