As the others have already noted, there is no such thing as a list of below market rate rentals. There are below market rate homes for sale available to government workers and people whose income and circumstances allow them to qualify for such programs, but this does not apply to transient housing, like apartments and rental units.
If you are needy and have low income that can qualify for this program, the County's housing authority provides Section 8 programs for those seeking housing. Keep in mind that even though the County can provide the program, landlords do not need to make homes available to the Section 8 Program, which is why I understand it can be hard as hard for Section 8 renters to find housing as for those without assistance programs.
Your best bet to finding housing is to be diligent, work with a reputable Realtor, and be aware of rental scams. Good luck!