OK, now I get it, you want to know if this is a collectible subject to the 28% rate.  IRS would probably say that it is, and that they are entitled to add it to the list even after the sale is made and the return is filed.  Also, that Congress meant to give them that authority.  Others might say that it's not what was intended by "collectible" at all; everything is collectible, by someone.  Tell your clients it's a grey area and let them decide how much risk they want to take for how much tax is involved.