If you like the closet cosplay idea, I have an entire collection dedicated to cosplays that you can make from items you probably already have.
Unlike most superheroes, America doesn't dress up to be a hero. She wakes up like this. Her color scheme is very consistent: red, white, & blue, with some gold and black. All of her outfits reflect her superhero identity Miss America, but her sense of style is very modern and accessible. So capturing her style can be very easy!
The goal here is simplicity and silhouette. America wears clothing that adds bulk to her already muscular arms and shoulders, but often leaves her legs bare. If you add anything, is should be a patriotic belt buckle, like this one.
This is where America's superhero identity shines through. If you can, grab your Fourth of July gear (like this sweatshirt) and flaunt it!
America tends to wear really subtle jewelry and really loud accents. What does that mean?
A lot of her clothing has a very DIY feel to it. Hand-sewn patches will make anything you own look really patriotic (and you can always remove it later).