This Sam Shakusky costume from Moonrise Kingdom is relatively easy to make, the only thing you have to boy is the hay which is like a racoons tail and can surely find it in any gun store or any 99 cent store. The shirt I knitted some buttons onto it I had from the past that were just not used and I made the star, and badges with yellow felt. The eckerchief is yellow felt as well but I got it wet and rinsed so it would look more like actual fabric and not a cloth.
You just need a khaki shirt, a khaki short, knee high socks, a coon hat and some reliable hipster glasses. If you wanna go all in get one of those camping backpacks that are really big, or you can get binoculars or a fake shotgun the kind you go shooting or a bow and arrow which are protagonist is so good at using