If you're a frugal shopper, this Miss Selfridge Open Cardigan will fit the bill. It's a fail-safe choice, while not very pricey. Another strong contender for your wardrobe is this Open Cardigan. While the price of this piece is not very high, it will certainly attract a lot of attention. You might also want to consider this Nic+Zoe Open Cardigan. The price is very reasonable, but the effect on your wardrobe will be pretty fantastic.
For something in the middle of the price range, you're in luck with this Nic+Zoe Open Cardigan in stock and waiting for you. You are guaranteed to love this piece. You can also look at this Open Cardigan. It's an attractive option both price and quality-wise.