If you're on a thrifty budget, this Nasty Gal Beanie will fit the bill. It's a foolproof choice, while not very costly. Another good option is this River Island Beanie. While the price is not very high, be sure that this item will become a great addition to your wardrobe. You might also want to consider this Hat. The price is very reasonable, but the effect on your wardrobe will be pretty fantastic.
If you can afford to splurge, take a look at this No.21 Beanie - a great luxury choice. While you're at it, also have a look at this Ermanno Scervino Beanie. Yes, this item is expensive, but it does not mean it's not worth it.