A v-neck sweater is a sound investment in comfort. Wear it with denim or layer it over crisp shirting, accessorize with a tie and pair with tailored trousers for a sophisticated look.
If you're on a thrifty mission, your best bet is this Nike V-Neck Pullover. It's a fantastic item, while not very costly. Another strong contender for your wardrobe is this Nike V-neck Sweater. While the price of this piece is not too high, it will certainly attract a lot of attention.