Though I support that ideal, I question whether approaches like this are effective ways to achieve it, or even push things towards it at all - Etsy is basically throwing reasonably large amounts of money ($5k apiece) to get people that have already expressed a strong interest in tech to...continue expressing their strong interest in tech.
It's like the customer has already started entering their credit card number as the final step of a purchase, and you're spending all your development time optimizing the wording of your product description on that final page because you really want to make sure they finish entering that credit card number. You've already made the sale, spend your time worrying about something else!
What I'd much rather see is a focus further up the funnel, where you can actually affect people's behavior and choices in some meaningful way. Spend that 50 grand by offering, at a select set of good schools, $100 apiece to the first 500 freshman girls that enroll in a real CS course, and I'll cheer the effort - $100 bucks is a small price to pay to know that a smart girl at a good school is taking a programming class, but it just might be enough so that you actually see an increase in enrollment. If it's not and nobody bites, bump it to $200 the next semester, see if it changes. Keep the sample of schools small enough, and you'll at the very least be collecting some interesting data on how much money it actually takes to convince college girls to take CS classes. [I suspect even a $100 incentive would be enough to get female enrollment on par with male for intro classes, since at most schools an intro CS class will satisfy some sort of distribution requirement anyways]
If we can get girls into first-year CS classes, we will see more women enter the field, I guarantee that. Not all of them, but some, and some of them will be fantastic. It might be crass, but I have no problem with bribing them. I'd happily contribute a few thousand to the effort if there was a sizable one set up.
But if we're going to resort to bribery, let's at least make it cost effective. Bribing a tiny set of people that are already going to do what you want anyways is not a smart approach, not when there are so many more creative options.