If you're after a thrifty option, this D&Y Beanie will fit the bill. It's a great choice, while not very pricey. Another strong contender for your wardrobe is this Halogen Hat. While the price of this piece is competitive, it will certainly attract a lot of attention. You might also want to consider this Beanie Hat. The price is very reasonable, but the effect on your wardrobe will be pretty fantastic.
If you want to splurge, then you absolutely must check out this Ermanno Scervino Hat. This item seems expensive, but it's top quality.