If you are on a tight budget, your best bet is this Volcom Tank. It's a terrific piece, while not very expensive. Also consider this RVCA Tank. It's a product you're bound to love which also won't break the bank. You might also want to consider this rhythm Tank. The price is very reasonable, but the effect on your wardrobe will be pretty fantastic.
If you're looking at it like an investment piece, then you won't be disappointed if you check out this Fear Of God Tank. It's a costly but smart option. While you're at it, also have a look at this Ann Demeulemeester Tank. Yes, this item is expensive, but it does not mean it's not worth it. Also take a look at this Nike Tank. You won't regret the money spent!