If you're budget-restricted, your best bet is this Beanie Hat. It's a wonderful item, while not very costly. Another savvy option is this David & Young Knitted Hat. While the price is not very high, be sure that this item will become an excellent addition to your wardrobe. You might also want to consider this Herschel Knitted Hat. The price is very reasonable, but the effect on your wardrobe will be pretty fantastic.
If you can afford to spend a little more, you're in luck with this White + Warren Beanie Hat in stock and waiting for you. You are guaranteed to love this piece.