If you're a frugal shopper, your best bet is this Echo Beanie. It's a wonderful piece, while not very pricey. Why not also consider this Rebecca Minkoff Hat. It's an item you'll love which also won't break the bank. You might also want to consider this Kate Spade Hat. The price is very reasonable, but the effect on your wardrobe will be pretty fantastic.
If you're looking for an item in the middle of the price range, consider this Echo Beanie. While the price is very reasonable, this product is an easy wardrobe update. It's also worth looking at this Inverni Knitted Hat. This product is extremely popular and, just as importantly, not too pricey. Consider this Helene Berman Beanie too! Great value for your money.