Armslist, uncheck the boxes for premium vendors and trades, filter by state and county

plenty of people selling shotguns and bolt actions and usually a few semi rifles that aren't double price (most of the ARs in my area are double or triple priced at this point, but not all of them)

if you don't mind driving to meet some random dude it's a great way to get never been registered stuff for only mildly gouged prices