only the "S" mint mark and the Reverse Proof can be certified as coming from the 25th Anniversary set as the other 3 coins have been released during this year and can not be proven as coming from the set.

Last I heard the unopened box was being offered at $1100, the "69" set at $1300 and the "70" set at $2800 - so you can see the reason for only buying unopened boxes as they are certifiable as a set.