Depending on where you would like to live, you'll need to see if that county/ city has a HUD approved housing authority. I work a lot with the Oakland Housing Authority which is the local organization in the city of Oakland that disperses HUD funds through their section 8 program. In Oakland there are about 14,000 vouchers available to assist precipitants with housing costs. On average it take up to five years on the waiting list before someone is approved. Applicants are granted a voucher based on a lottery system, not on the basis of need, unfortunately.
I think I read somewhere that the city of Pittsburg or Antioch has something on the order of 1,800 vouchers active at any one time. Voucher turn over is very rare, as you can imagine. Good luck with your search.