Lucy, Lady Duff-Gordon (1863 - 1935) was the leading fashion designer during the late 19th and early 20th century, she was the originator of the modern fashion show which she called the mannequin parade and the first to use professional trained fashion models. Her fashion designs were revolutionary for the era.
Duff-Gordon was also a Titanic survivor.
Here we have her exclusive catalog for the 1916 season produced by Sears Roebuck, you can see the difference in the model posing compared with other catalogs of the era.
To bring the price of the garments to 2019 dollars multiply the amount by 25, quite expensive for a mail order dress