The trench coat is a timeless piece in between seasons that also does a great job of protecting you from the inclement weather. Throw on your trench coat over everything from relaxed denim to more refined pieces.
If you can’t spend much, your best bet is this Asos Trench. It's a wonderful product, while not very expensive. In this price range, you can also check out this Asos Trenchcoat. It's a product you'll love which also doesn't cost a fortune.