If you're on a thrifty mission, your best bet is this Nike Tank. It's a fantastic piece, while not very expensive. Another strong contender for your wardrobe is this Express Tank. While the price of this item is not too high, it will surely attract a lot of attention. You may also want to look at this Catherine Malandrino Tank. 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, look no further than this Beyond Yoga Tank. This item doesn't cost too much, but absolutely essential in your wardrobe. You can also check out this Vimmia Tank. It's an attractive option both price and quality-wise.