There are plenty of purveyors of old barns. Try a web search for 'used barns', 'reclaimed barns', 'recycled barns', etc. I'm avoiding mentioning any by name in order for you to have an objective search. Re-post here if you can't come up with a few names of interest. There many who frequent this forum who can advise you with as much (or more) information than you could possibly want!