For something in the middle of the price range, look at this N.Peal Beanie. While the price is very reasonable, this piece is an easy wardrobe update. It's also worth taking a look at this Stella McCartney Hat. This product is extremely popular and, just as importantly, not very expensive. Alternatively, opting for this Etoile Isabel Marant Hat is a great choice as well!
If you can afford to splurge, then you won't be disappointed if you check out this Thomas Wylde Knitted Hat. It's an expensive but smart option. While you're at it, also have a look at this The Elder Statesman Hat. Yes, this item is expensive, but it does not mean it's not worth it. Another good option is this Beanie. You won't regret the money spent!