Beige Cardigans from mytheresa
If you're a thrifty spender, your best bet is this Open Cardigan. It's a popular piece, while not very pricey.
For something in the middle of the price range, why not take a look at this Acne Studios Cardigan. While the price is very reasonable, this piece is an easy wardrobe update.
If you want to splurge, then you won't be disappointed if you check out this The Row Open Cardigan. It's a costly but smart option.