If you'd rather not spend much, this Zella Tank will fit the bill. It's a foolproof choice, while not very costly. Another savvy option is this Nic+Zoe Tank. While the price is rather reasonable, be sure that this product will become a great addition to your wardrobe. You may also want to look at this Lush Tank. This item is not expensive either, but it will make a difference in your wardrobe.
If you're after a bargain, look no further than this Misook Tank. This item doesn't cost the earth, but definitely deserves a place in your wardrobe. It's also worth checking out this Maison Margiela Tank. This product is ultra popular and, just as importantly, not very expensive. And do check out this The Great Tank! It's a very popular item and good value for money.