For something in the middle of the price range, why not opt for this Paige Duster. While the price is very reasonable, this product is an easy wardrobe update.
If you're not a thrifty type, consider purchasing this Chloé Duster Coat - a great luxury choice. While you're at it, also have a look at this Fuzzi Duster Coat. Yes, this item is expensive, but it does not mean it's not worth it.