If you are on a limited budget, this Nina Brooch will fit the bill. It's a foolproof choice, while not very pricey. In this price range, you can also check out this Leith Brooch. It's also a popular item and won't break the bank. You may also want to look at this J.Crew Brooch. This item is not expensive either, but it will make a difference in your wardrobe.
If you're looking for a happy medium, why not consider this Etro Brooch. While the price is very reasonable, this piece is an easy wardrobe update. Also consider this Marni Brooch. It's an attractive option both price and quality-wise. And do check out this Kenneth Jay Lane Brooch! It's a very popular item and good value for money.