Black Kimonos from Off 5th
If you're a thrifty spender, consider buying this BCBGeneration Kimono. It's a fantastic piece for a reasonable price. Also take a look at this 1 STATE Kimono. It's an item you'll fall in love with which also won't break the bank.
If you're looking at it like an investment piece, then what you're looking for is this Helmut Lang Kimono. It's more expensive but worth your money.