If you'd rather not spend much, you'll appreciate this J.Crew Turtleneck. It's a fail-safe choice and a great investment. In this price range, you can also look at this Old Navy Rollneck. It's also a popular item and won't break the bank. You might also want to consider this Asos Rollneck. The price is very reasonable, but the effect on your wardrobe will be pretty fantastic.
If you're looking for a bargain, check out this Rollneck. While the price is very reasonable, this product is an easy wardrobe update.