If you'd rather not spend much, this J.Crew Rollneck will fit the bill. It's a popular choice, while not very expensive. Another good option is this J.Crew Turtleneck. While the price is not very high, be sure that this product will become a valuable addition to your wardrobe.
If you're after a bargain, consider buying this J.Crew Turtleneck. While the price is very reasonable, this piece is an easy wardrobe update.