I agree with Doug! Unless the coins are PF-69 to PF-70, you are better off leaving them in the set! Besides with the exception of the 1995-W Gold Eagle and Silver Eagle Set, the 1999-S Silver Proof Set has out performed most other sets of coins minted in the last Century as far as rise in value from issue price to their' high. Sure, they have been in a lull value wise for awhle but I believe that will soon start a slow creep upwards in value and will continue to rise over the years. Don't forget to check the 1999-S Proof Lincoln Cent to see if has the "AM" close together in "AMERICA on the Reverse (Close AM Business Strike Reverse Error Cent)! If it does have this Error Cent, then you can sell the Proof Set for a premium or break up the set and sell the Cent individually. This is a time, when you might want to have at least the Cent cerified, graded and attributed by PCGS which will significantly increase the value of the Error Cent. Frank
