If $500 seems expensive you might not be ready to start paying somebody $5000 every month, not to mention all the additional expenses that come with having an employee.
You could advertise for 10 months for 1 month salary and it might take that long for an employee to get up to speed and actually contribute anything useful. If you hire the wrong guy it could take longer before they are useful. Not to mention the additional drain on your time as you teach them about your codebase and how you do things.
If you hire the wrong person and have to let them go after a month or two you are out of pocket $20k and back to square one. (And if its not working out I suggest you be prepare to make this tough call)