Frank, with just the serial number you gave, without any other inforamtion it looks to be 1936. You didn't mention what ga, barrel length, etc. All these things mean a lot as far as determining a price. A 16 ga., or 20 ga., will bring more, longer barrels will sometimes do the same. Case coloring %, blueing etc. Also with out seeing the gun, and looking at it very carefully, making sure all serial numbers match, it is next to impossible.
Blue Book of Gun Values 26th Edition lists a 12 ga. Field Grade with 70% at $650.00 and at 60% $600.00. If it is a 20 ga. add 50%, a 16 ga. add 33%. If you are really interestd in the gun offer him less. Just make sure everthing works, see if the screws holding the sideplates and trigger plate are not all buggered up, means it was taken apart by someone not using the right tools. Let us know how you make out, and if you get it hope you will join the L.C.S.C.A. Happy New year