That is a big barn unless you have plans to fil it with machines, hay/straw or even animals. A low cost option would be a 2 sided hanger made of timber and sheet metal. They work well if positioned against prevalling winds. We use our hanger more than the barns. Infact the chicken live in one and the other is not used at all except for the cellar beneath it.
A large barn may sound attractive but we do not use them as much as I thought we would. The metal sheet hanger is excellent to park under, store tools, logs and to do jobs under.