If you're looking for a thrifty option, your best bet is this MET Crew-neck T-shirt. It's a popular product, while not very expensive. Another good option is this Only Crew-Neck Tee. While the price is rather reasonable, be sure that this product will become a valuable addition to your wardrobe.
If you're looking for a happy medium, why not check out this Vanity Crew-neck T-shirt. While the price is very reasonable, this item is an easy wardrobe update.