I am a bonafide hoarder of white button-down shirts. Since they often get stained season to season, I'm always looking for affordable options and recently, I discovered these men's non-iron button down shirts at Uniqlo which have quickly become a favorite. As mentioned, they are indeed in the men's section, but lucky for ladies, they go all the way down to size XXS. Since the style right now is to be slightly boxy and masculine in silhouette, the fit is absolutely perfect and for under $30, I've hoarded them in every color.
FYI, if you haven't purchased non-iron button-downs before, you're in for a real treat. I have lots of similar classic cotton button-up shirts, but the constant need to iron them after every wash means I end up reaching for them much less frequently. Not the case with these beauties which are good to go after the dryer.