According to the COA, the 2002 West Point Commemorative Silver Dollar is supposed to be a Proof. However, from the pics which I know can be deceiving, the coin appears to be a Mint State 2002 West Point Commemorative Silver Dollar which is Silver and Clad Mint State coin and not a Proof. If the commemorative coin is in fact a DCAM Silver Proof, then it is worth between $30 and $35 based on eBay, PCGS' Price Guide and Numismedia's (NGC's) Price Guide. It is doubtful that you could get a the coin in a DCAM Silver Proof with box and COA for $20 but maybe $25! Whatever you pay, just make sure that it is not a Mint State Sliver/Clad that has been placed in a DCAM Silver Proof box.
Frank