If you're not planning on spending much, this J.Crew Padded Vest will fit the bill. It's a popular choice, while not very pricey. Another strong contender for your wardrobe is this J.Crew Tank. While the price of this item is competitive, it will surely attract a lot of attention.
If you can afford to spend a little more, look no further than this J.Crew Blouse. This item doesn't cost too much, but absolutely deserves a spot in your wardrobe.