Lots of places have local sales papers like the Thrifty Nickel, Peddler, either on line or in paper form. Facebook often has area "for sale" groups, just google stuff for your area.
Pawn shops usually carry guns and you have plenty of time to shop (or save up a little more money) before spring. Good luck in your search.
Avoid rusty guns, check to see that the choke isn't frozen in the barrel, work the action and try the trigger before you buy one. If one of those guns you mentioned pumps without binding, and all the rest is in order, you should be OK in buying one.