If you are on a tight budget, this J.Crew Turtleneck will fit the bill. It's a great choice, while not very expensive. Another strong contender for your wardrobe is this J.Crew T-shirt. While the price of this piece is not too high, it will surely attract a lot of attention.
If you can afford to spend a little more, why not consider this J.Crew V-Neck Pullover. While the price is very reasonable, this piece is an easy wardrobe update. It's also worth considering this J.Crew Tank. This item is ultra popular and, just as importantly, not very expensive.
If you want to splurge on a luxury piece, then you won't be disappointed if you check out this J.Crew Long Sleeve T-shirt. It's an expensive but smart option.