If you are on a budget, this Zella Tank will fit the bill. It's a popular choice, while not very expensive. You might also want to consider this Nic+Zoe Tank. It's an item you're bound to love which also won't break the bank. You might also want to consider this Nike 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, why not take a look at this Alo Tank. While the price is very reasonable, this piece is an easy wardrobe update. Why not also check out this Misook Tank. It's an attractive option both price and quality-wise. And do check out this Current/Elliott Tank! It's a very popular item and good value for money.