As Dave said, it is a great gun. Prices on them can have a pretty good spread depending on condition and how many are available in the area, (some places you almost never see a used one in a store, others will have a bunch.) $300 is about the lowest I've seen any model Browning (Auto-5, A-500 light or mag, Belg. or Jap) even ones that are absolutely beat to hell, with no finish and the barrel chopped down to mount either a
Cutt's Compensator or other old multi-choke twist things (ugly as sin). Beyond that, they will go as high as the dealer thinks he can get. I did spot an A500 mag in a shop the other day, excellent shape, about 95% for $425, best price I've seen on one in a long time.
Bergie