What do you want to do with it? What gauge? Single or double triggers?
I am very partial to Marlin Model 90's. They were made between 1937 and 1957 (DT's). ST's were sold from 1954 to 1963. They come with fixed chokes, Mod/full in 28" barrels and IC/Mod in 26" barrels, and extractors. You should be able to find a decent 12 ga. for around $300-$350. ST's sell for more, as do 16 ga. and 20 ga. Model 90's. 16 ga. and 20 ga. guns were made on the same size frame that is smaller than the 12 ga. frame
I think they handle and shoot great ( I have 13 in various gauges and barrel lengths) and they are durable. I got my first 12 ga Model 90 used in 1957 or 1958 (still have it). Weagle posted on the Shotgun World web site last year that he had shot over 25,000 rounds through his used 12 ga. Model 90 DT without any problems.
My favorite upland bird gun is a 16 ga. Model 90DT with 26" barrels made in 1947.