I see a lot of them around ....for $ 300 - $ 500 for the most part / in above average to very good condition.
Value - to the buyer - to some extent / depends on what its choked at.
Most anyone that wants an Auto 5 ...has one / ....including me ( its in the back of my safe / hasn't been fired in 20 yrs ..belonged to my grandfather )...don't know why I hang onto it ...don't really want it ...don't really want to sell it ..( I have 20 or more other shotguns to shoot ....lots of Browning Citori O/U's ...and Benelli semi-autos)...
Auto 5's have their following ...but they aren't "collectable" really or valuable. They have nostalgia ...they were the semi-auto of my youth ...and everyone had one around. Shoot it and enjoy it for what it is ....is my recommendation.