@Sam Leon If the area doesn't demand the locks, then I would not spend the time and money on them. Just buy the ones from HD or Menards that are simple and easy to install. I just went through the headache of changing out several locks on the mailboxes at my apartment building here in Berwyn, and I can tell you that the job is easy but time consuming! The mail boxes were already existing, so I had no need to do a replacement. In my South Bend 20 unit, I use only the cheap mailboxes with no lock.
Keep it simple is always your best business approach. If tenants have keys they will lose those keys. Use a basic box with a small hasp and they can install their own locks and be responsible for lost keys.