If you're looking for a thrifty option, this Topshop Tank will fit the bill. It's a great choice, while not very expensive. Another strong contender for your wardrobe is this Topshop Tank. While the price of this piece is competitive, it will certainly attract a lot of attention.
If you're looking for an item in the middle of the price range, consider this Topshop Cropped Top. While the price is very reasonable, this item is an easy wardrobe update. Why not also consider this Topshop V-Neck Tee. It's an attractive option both price and quality-wise.