It's just not worth the trouble.
On a similar note, there are those who have a table of guns at a gun show with no prices on anything. You're really interested in the gun but the table holder is off somewhere or he is having an extended conversation with a buddy about the price of tea in India. Again, just not worth the trouble.
How many times have you walked up to a table full of guns WITH prices on them and then waited for the tea in India conversation to end to see if the dealer would negotiate on the price? No difference. If it's a gun you're interested in, you'll wait and talk to the dealer anyway.
Alot of times the dealers do not list prices and use POR to prevent being undercut by the dealer down the aisle or across town.