The open cardigan is perfect for transitioning from summer to fall. A relaxed, open cardigan will look great layered over a basic tee and jeans.
If you're after a thrifty option, this Asos Open Cardigan will fit the bill. It's a fail-safe choice, while not very pricey. Another strong contender for your wardrobe is this Asos Open Cardigan. While the price of this piece is not too high, it will definitely attract a lot of attention.