If you're budget-restricted, your best bet is this Bailey 44 Rollneck. It's a wonderful product, while not very costly. Another good option is this Eileen Fisher Rollneck. While the price is rather reasonable, be sure that this item will become an excellent addition to your wardrobe. You may also want to look at this Sejour Rollneck. This item is not expensive either, but it will make a difference in your wardrobe.
If you're looking for an item in the middle of the price range, consider this Equipment Turtleneck. While the price is very reasonable, this piece is an easy wardrobe update. It's also worth looking at this Eileen Fisher Rollneck. This item is extremely popular and, just as importantly, not too pricey. Check out this IRO Rollneck too! Great value for your money.