Four designs exist. Silver proof. Brass uncirculated. Brass proof of silver design. Brass proof of brass uncirculated design. Over the years, I have seen a few silver proof medals, many brass uncirculated medals and two sets of the brass proof medals. Both sets of the brass proof medals were seriously impaired (which could not be resolved with conservation efforts). Price should be related to rarity and condition. The silver and brass proof medals are rare, extremely rare in unimpaired condition and always seem to be "expensive." The brass uncirculated medal is readily available in 65-67 condition and always seem to be "inexpensive." Still, "expensive" and "inexpensive" are words which vary with each collector. And, remember, Arif's warning (about hoards) is very realistic and a persistent danger. I never forget this risk when adding items to my collection.
Mark Bonke