I have another cheap one to recommend, <$10:
Beechfield Unisex Outdoor Waterproof 6 Panel Baseball Cap on Amazon
Shallow crown, so great for exercise or small heads. Comes in a handful of colors: black, light grey, navy blue, & olive. Don't expect perfection, but it's great for the price.
I bought this from Amazon, pretty decent quality and nice stretchy band with a clasp as well. I feel like it should be a staple in everyone's wardrobe.
Here's a few. I have the beechfield one from amazon and it's held up pretty good despite the fact that I use it a lot.
There's a comparison review between the reigning champ and outlier one somewherr in /r/outlier.