If you're looking for a thrifty option, this Forever 21 Tank will fit the bill. It's a popular choice, while not very pricey. In this price range, you can also check out this Tank. It's also a popular item and won't break the bank. You might also want to consider this Chaser Tank. The price is very reasonable, but the effect on your wardrobe will be pretty fantastic.
If you're a bargain hunter, look no further than this 3.1 Phillip Lim Tank. This item doesn't cost too much, but definitely deserves a place in your wardrobe. It's also worth taking a look at this Etoile Isabel Marant Tank. This product is extremely popular and, just as importantly, not very expensive.
If you can afford to splurge, then you won't be disappointed if you check out this Marni Tank. It's a costly but smart option. While you're at it, also have a look at this Courreges Tank. Yes, this item is expensive, but it does not mean it's not worth it.