No one can know everything about long guns and pistols and those in Gun Librarie's fall victom to this. When you have special knowledge you will always recognize true value and a bargain when you see one. The people buying and running the Gun Rooms might have general knowledge or ever great knowledge in some areas but not all. There are just too many different guns, too many different options or variations to be able to accurately price most guns.
We laugh at the $500 gun priced at $4000 and grab the $4000 guns priced at $1000. But if they listed the 4k gun at 1K you have to know they bought it for less than that. Only items in their inventory for years get marked down to bargain prices unless they are bought cheap, not recognized for their true value and priced to sell based on thought to be value or as a simple markup of the purchase price.
I love walking into the Gun Libraries because I often get one of two things. A good laugh or a chance to buy something at a bargain price. I'm good either way. I just bought a Remington Model 12 B in .22 short, also know as a Galley Special for $200.00, "because it did not shoot long rifles .22". Never mind that it is somewhat rare in high condition it was odd and hence not worth much to them. So I bought a 80-90%% gun for about 20% of its real value. Sent it to a buddy who collects them and he was thrilled to get it at what even to him was a bargain. Laughing all the way to the bank on that one.