You only have to like a property facebook page once to get a code. After that, the same codes can be re-used day after day (there are a few exceptions). Get a code, write it down, repeat 9 more times, and re-enter the same codes every day.
There are actually -other- discussion boards where long lists of codes have been posted.
As I said before, be sure to unlike the properties later, or your personal FB page will be inundated with ads.
- bcc