I'm in love with this fashion, and the type of dresses that marilyn monroe, bette davis, elizabeth taylor, and other actesses wore in this era. I want a knee length dress with a flowing skirt, not pencil skirt which is what I'm finding everywhere. If there are any websites where I could find a dress id really appreciate it :)

eBay.
Tons of them, grouped by years and sizes.

Check out http://www.ehow.com/how_8455463_create-1950s-look.html for tips on creating the 19500's look, including fashion, makeup and hairdo.