If you're not planning on spending much, your best bet is this Free People Scarf. It's a terrific piece, while not very expensive. Another strong contender for your wardrobe is this Saachi Scarf. While the price of this piece is rather reasonable, it will certainly attract a lot of attention. Or you can opt for this Pendleton Scarf. This item has all the potential to become a powerful player in your wardrobe.
If you're willing to splurge, then what you're looking for is this Y's by Yohji Yamamoto Scarf. It's more expensive but worth your money. While you're at it, also have a look at this Burberry Scarf. Yes, this item is expensive, but it does not mean it's not worth it. Also take a look at this Y's Scarf. You won't regret the money spent!