To be honest, cash prise or none, the only way you'll get programmers interested in your project is by posting a well thought-out and comprehensive design document. Remember the programmers on this forum aren't professionals, they don't do this for money, they do it because it interests them. In order to entice programmers, you'll need to do something to capture their imaginations, as well as their wallets. Most programmers will deliver the moon on a stick for free, if the moon is challenging and interesting to them.