If you're on a thrifty mission, your best bet is this Zella Tank. It's a great piece, while not very pricey. Another wonderful option is this Exofficio Tank. While the price is rather reasonable, be sure that this item will become an excellent addition to your wardrobe. You might also want to consider this Johnny Was Tank. The price is very reasonable, but the effect on your wardrobe will be pretty fantastic.
If you're looking for an item in the middle of the price range, look no further than this Lafayette 148 New York 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 Vince Tank. This piece is ultra popular and, just as importantly, not very expensive. And do check out this Wilt Tank! It's a very popular item and good value for money.
If you have enough to afford it, then what you're looking for is this Alice + Olivia Tank. It's more expensive but worth your money. While you're at it, also have a look at this A.L.C. Tank. Yes, this item is expensive, but it does not mean it's not worth it.