To begin with, there are Mint sets and Proof sets, and they're 2 different things. You'll need to check your set to determine which kind you have.
Mint sets are sets of uncirculated coins selected from normal strikes. These retail for about $15 to $20.
Proof sets are specially-struck coins that have mirrorlike surfaces and matte-finish images. 1995 proof sets sell at a fairly decent premium - cupronickel sets retail for $35 to $45, and silver sets are in the $80 to $90 range.
With original Mint packaging retail is $30.00 for a Silver Proof Set
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
Proof sets were not made in 1965, but a 1965 special mint set is worth $12.00 USD.
With original Mint packaging retail is $30.00 for a Silver Proof Set
Issue price was $21.00. Current average retail price is $61.00.
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.
The 2006s 10 coin proof set has a retail value of $31.00 issue price was $16.95
Current value of the 2003 10 piece Proof set is $10.00. Issue price was $19.95.
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.