An amusing thread.
Informing the shop of the value is NOT the OP's topic.
His topic is the fact that he does not want to do a 4473 on a gun when the law does not require it.
No 4473 is required for an antique.
However, he is afraid the magic word- "ANTIQUE" will make the price go UP.
It is a moot point.
They have already entered it into their firearms log.
They have to show a disposition in that log.
For every other gun in that log, they show a 4473 or an FFL.
They do not have an option to show "Antique entered by mistake".
They will not sell it without getting a 4473 or an FFL.
So, you might as well keep quiet about the Antique status and take the hit. Unintended consequences can bite ya!
AFTER you own it, educate them if you want to.