ebay search under "j crew linen tunic dress" - then(if there isn't one you want to bid on now) "add to favorite searches" and sign up for email alerts so that you will know when your size is listed- HTH
For the same style you could search for "Salwar Kameez" That is the name for a traditonal dress worn in central Asia. I bought a few while in India just for the tops. They are usually long tunic style like the Jcrew one.
Hmm, I'm not sure ebay would be the best idea, just because dresses are extremely hard for me to find that fit correctly. Most of the time it'll fit on one half of my body, but not the other, so trying on is usually a must