If you are on a tight budget, your best bet is this Nic+Zoe Tank. It's a popular item, while not very costly. Another strong contender for your wardrobe is this adidas by Stella McCartney Tank. While the price of this item is competitive, it will definitely attract a lot of attention. Or you can opt for this Asos Tank. This item has all the potential to become a powerful player in your wardrobe.
If you're looking for a bargain, look no further than this Alexander Wang Tank. This item doesn't cost too much, but absolutely invaluable in your wardrobe. You might also want to consider this BCBGMAXAZRIA Tank. It's an attractive option both price and quality-wise.
If you're willing to splurge, then what you're looking for is this A.L.C. Tank. It's more expensive but worth your money.