You've seen its picture in the window, but that may be the only place you'll see Ann Taylor's Vintage Floral Sheath Dress.

The sleeveless sheath, seen now on Milla Jovovich in the chain's window displays, and on Hilary Rhoda (left), has sold out in New York stores in a record two days.

What's more, 11 of these dresses have turned up on eBay, where bidders have pumped the $198 retail price to up over $200, with one dress already at $300 -- and there's another day of bidding left!

The good news is that the company is mobilizing to get more of these apparent must-have dresses in stores.

There are 100 additional Vintage Floral Sheath dresses that will be available through a flash sale as early as next week -- definitely in time for Memorial Day cookouts.

Check back here for the latest on this sellout.

Meanwhile, read about Ann Taylor's new look.