I'm new to this forum, and too late for the arbitrary date that was placed, but I've got to say, this thread seems to be the complete opposite of how crowdfunding should work.
If money is the motivating factor for someone looking to write this software, it would be much better for everyone if they set up their own crowdfunding campaign. They'll know how much they'll need to cover their living costs etc far better than you. They won't run the risk of putting months into it with no guarantee of payment (in the unlikely case of multiple people rising to this challenge). There's an unnecessary step in the middle (you), who's taking payment for something that doesn't even exist on the promise of paying it to someone you deem worthy. Have you even considered the lax liabilities you could be opening yourself up to? The success criteria is also vague and subjective.
More significantly, should you even be rewarding the FIRST such project anyway? What if someone submits something that does everything you requested, but the UI feels clunky and unpleasant to use. A month or 2 later, imagine something better comes along that's a joy to use, but you've already given away your crowdfunding money for something that now nobody even wants to use.
Consider the Raspberry Pi Quake 3 bounty. All the money came from corporate sponsorship and was a significant amount ($10000) to try to encourage people to create an open-source GL for the RPi. And yet 3 years after the winner was announced, there's still a long way to go despite lots of work by countless other people and the whole bounty seems like it was a bit of a sideshow.
But in any case, even with your 15 people so far that's only $380 up for grabs. That's a nice perk if you happened to be already writing such a thing (in which case you don't need the incentive), but no way near enough to even consider as compensation for the work required.
I guess what I'm saying boils down to:
- As a potential customer, I'd much rather fund someone who's actually doing the work.
- As a potential developer, even though I'm perfectly capable of making the exact thing you want, there's nothing in this campaign that'd entice me to put my projects aside to work on it.