Is it possible to unlock every character without using Bux? [duplicate]

Which characters in Tiny Death Star can be unlocked without paying in Imperial Bux?

All the events are random generated:

• new species
• unlocking a character
• finding a character on a certain level
• unlocking scenes
• etc.

So you can unlock any character within the game, and any scene / level / race by random chance.

These seem to unlock in a prescribed order:

Bounty Hunters: Boba Fett, IG-88, Dengar, Greedo, 4-LOM

Droids: C-3PO, FX-7, R5-D4, Pit Droid, Interrogation Droid, (1? still locked)

Men of the Rebellion: Lando, General Lando, Han Solo, New Hope Luke, (5? still locked)

Ladies of the Rebellion: Bespin Leia, Leia Organa(Rebel), Hoth Leia, Endor Leia, Slave Leia

Rebel Heroes: All unlocked.

Rebel Aliens: Bothan, Ewok, Gungan, Mon Calamari, KelDor, Sullustan (2? still locked)

Outer Rim: Chiss, Gand, Geonosian, Jawa, Toydarian, Ugnaught, Zabrak (4? still locked)

Troops: All unlocked

Rebel Forces: All unlocked

The Force: Emperor Palpatine, Obi Wan Kenobi, Jedi Luke (2? still locked)

Cantina Crew: Aqualish, Arcona, Chadra-fan, Rodian, Snivvian, Devaronian, Duros, Kubaz (3? still locked)

Hutt's Henchmen: Gran, Twi'lek, Weequay, Gamorean, Lando Calrissian (Skiff)

Limited Edition: Boba Fett (Holiday Special), 3? Locked

I know you can click on the ?s and see who they are, I just didn't feel like typing all of them out here.

Aqualish also unlock automatically.

Based on your list, which is identical to mine except in that regard, I'm guessing that they unlock on a schedule. It may not be in the same order.

I suspect that they unlock in threes: three new characters, three new races, usually in a relatively sport span of time, and then a long gap before the next unlock.

Interestingly, although Jawa and Duros have been unlocked, I've never had a bitizen of either race appear in the elevator except as part of a ? event.

UPDATE: Since I wrote that, KelDor (rebel aliens) and Weequay (Hutt's henchmen) have unlocked. I've also had Twi'lek show up as customers in my stores.