If you're on a thrifty mission, this Ben-Amun Pendant will fit the bill. It's a foolproof choice, while not very expensive. You might also want to look at this Marc Jacobs Pendant. It's an item you'll fall in love with which also doesn't cost the earth. You might also want to consider this Rebecca Minkoff Pendant. The price is very reasonable, but the effect on your wardrobe will be pretty fantastic.
If you're a bargain shopper, we've got your back with this Marni Pendant. This item is bound to become a total wardrobe staple. You might also want to consider this Sydney Evan Pendant. It's an attractive option both price and quality-wise. And do check out this Pamela Love Pendant! It's a very popular item and good value for money.