I'm trying to figure out the ballpark value to this pistol. A Colt 1991a1, it has some wear on the finish, Pachmayr grips (still have the original grips). I've added a match grade trigger and full length guide rod. It is one of the most accurate pistols I have ever fired. I've done some research online and found similar guns going for $900. I paid $600 for it about 15 years ago. Any help would be greatly appreciated.