If you're looking for an affordable item, your best bet is this Aqua Turtleneck. It's a wonderful piece, while not very pricey. Another wonderful option is this Free People Rollneck. While the price is not very high, be sure that this product will become a valuable addition to your wardrobe.
If you're looking for something in between pricewise, we've got your back with this Suncoo Turtleneck. This piece is likely to become a total wardrobe staple.