There were at least three women in home-made Flash costumes at Comic-Con International 2007, two of whom I met.
(Originally posted at K-Squared Ramblings)
(From CBR’s Photo Parade)
Looking online, I’ve spotted one more in a homemade costume (SDCC 2009), and several women wearing an off-the-shelf female Flash costume (SDCC 2009 and WonderCon 2010).
I guess it’s the same principle as the Ame-Comi statue of “Jesse Quick as the Flash.” The Flash is the more famous character. He’s got the name recognition, the costume recognition, and the fan base. More people are going to recognize you if you’re dressed in red with the Flash symbol on your chest than if you wear a random mix of red and yellow with goggles.
Come to think of it, though, if someone did want to design a Jesse Quick costume, she’d have a lot of leeway in what she could wear with it still being authentic!
FOLLOW-UP (Oct. 2011): Here’s an actual Jesse Quick cosplay from NYCC 2011.