Black Caps from Zappos
If you're looking for a thrifty option, this Converse Cap will fit the bill. It's a foolproof choice, while not very pricey. Another good option is this San Diego Hat Company Baseball Cap. While the price is not too high, be sure that this piece will become a great addition to your wardrobe. You might also want to consider this Arc'teryx Baseball Cap. The price is very reasonable, but the effect on your wardrobe will be pretty fantastic.
If you're looking for a bargain, why not take a look at this Ted Baker Baseball Cap. While the price is very reasonable, this item is an easy wardrobe update.