If you are on a budget, your best bet is this BaubleBar Necklace. It's a popular item, while not very pricey. Another strong contender for your wardrobe is this Madewell Necklace. While the price of this piece is not very high, it will definitely attract a lot of attention. You may also want to look at this Necklace. This item is not expensive either, but it will make a difference in your wardrobe.
If you're after a bargain, look no further than this Fallon Necklace. This item doesn't cost the earth, but absolutely indispensable in your wardrobe. It's also worth considering this Nach Necklace. This piece is ultra popular and, just as importantly, not too pricey. Consider this Necklace too! Great value for your money.