Sometimes you cannot get access to key blanks. That's okay. You can buy a bunch of locks and study similar keys that work. Or you can go the route of a smart key. This is a key that can potentially open multiple different locks. Just be warned that you might need to use a little force to budge the lock open.
If you do have access to some blanks, you can try a couple times to get through. The key (no pun) is to cut one key depth at a time. You might be able to create a key that works on multiple locks. You produce a master, then you become the master. Sounds like Star Wars, right?