I do have considerable luck on Saturdays by finding figures before 8 a.m. It's part of my Saturday morning routine to visit Wal Mart early, and, if stuff is showing up in other areas with some consistency, I will stop in before work. I try to stop on Thursday nights, too.
Other than the Ep. 2 sneak preview figures, I haven't found the last two waves (excluding Eeth Koth and Snaggletooth) at all. Very frustrating.