I hope you're not suggesting the price is too low..A full-time developer. Typically, that's 40 hours per week. There's 4 weeks in a month. So 40 x 4 = 160. $500 divided by 160 hours is $3.12. That's $3.12 an hour.
You're offering programmers slave wages when they're normally the highest paid skilled workers in this industry. Good luck, bud.