Vic George 2K6, your third favorite Supergirl costume was actually worn by the Earth-1 Kara Zor-El prior to the classic '70s "blouse and hotpants" costume (your #1 choice). The "mod" long gloves, hipboots and miniskirt outfit was created by Wonder Woman, during her depowered "Diana Prince" days when she ran a dress shop and fought crime as DC's version of Emma Peel. :wink: In reality, this costume was submitted by Barbara Reader of New Hyde Park, New York -- several costumes Kara wore in her Adventure Comics days came from fan solicitations.
For a scene of Diana's dress shop at the debut of this particular costume:
http://www.comictreadmill.com/CTMBlogarchives/2004/2004_Monthly/2004_09.php(September 9, 2004 entry)
For more Supergirl costumes (though some images were "borrowed" from this website's own Supergirl costume section):
http://forums.comicbookresources.com/showthread.php?t=55715