In Star Wars: A New Hope, Leia pays Han Solo his reward for rescuing her from the Death Star. We see him hauling his treasure in the rebel base in metal green boxes:
However, the Death Star destroyed Alderaan, Leia's home planet.
With her home planet, and presumably her assets, destroyed, where did Leia so readily get the money to pay Han Solo his reward?
Leia was a leader in the Rebel Alliance. She had other resources and contacts than her home planet. She did have to wait until they reached a Rebel base before she could pay him.
This is covered in the film's new Disney canon junior novelisation. In short, his reward (in the boxes we see on screen) is made up of precious metals that are evidently used in the repair of spaceships.
“We don’t keep that sort of money lying around,” Commander Willard said. “And this is…we need every cent to keep up our operations.” “I’m willing to accept the amount in precious metals if you don’t have the credits on hand,” Han said, crossing his arms over his chest. “Come on, pal, you don’t want word to get around that the Rebellion can’t honor their debts, do you? No one would be willing to do business with you.”
...
“Give him whatever he wants,” Leia said stiffly. The look she shot Han could have incinerated half the Death Star. “The sooner he gets it, the sooner he’s gone.”
A similar scene occurs in the earlier A New Hope: Junior Novelisation.
Stepping down to the hangar floor, Luke found Han and Chewbacca loading small boxes onto an armored military speeder. The boxes contained precious metals, the only form of currency that Han would accept from the Alliance. Han had insisted on the payment, even though the Rebels desperately needed the materials for repairing starships and equipment. Han appeared to be completely ignoring the activity of the Rebel flight crews and pilots.
Moving down the canon scale, this is also backed up in the (alas, now non-canon) Star Wars Radio Dramatization:
Leia: Captain Solo may have no morals whatsoever, Commander, but he's right. Both Luke and I promised him payment for his and Chewbacca's help in this matter.
Willard: Very well, I see I misjudged you, Solo
Han: I'll cry later. Right now, I'll settle for cash. In small, used notes if you've got 'em.
Willard: But this is a Rebel camp! We're hunted people, with very little Imperial currency among us!
Han: Oh. Well, your tech facilities must have stocks of precious metals.
Willard: Yes...
Han: They'll do.
Willard: But those are critical matériel! We need those metals for repairs, to keep our weapons and equipment functioning!
Princess Leia was a member of the Imperial Senate. So, she would have indeed assets on Coruscant as well as throughout the Galaxy. Even if we exclude "outside Coruscant", it wasn't a big deal for her to get credits in exchange of her Coruscant assets because Coruscant was a galaxy-class corrupted planet.
Assuming she didn't have a personal bank account somewhere she could access. She could very well have pulled some assets from the Alliance. As revealed through the books and other written media, Han was paid in credits, precious metals and spices. Getting the metals and spices suggests payment on behalf of the Alliance to be correct. Han's reward ended up getting stolen before he could pay it which is why Jabba was still after him.
Han Solo ‘likely’ received the monetary compensation that Obi-Wan Kenobi ‘would have received’ (or would have at least been offered) from the Rebel forces if he had rescued Princess Leia himself. Also, at the time Kenobi offered Solo the 17,000 credits for transporting him, Luke, and the droids to Alderaan he did not know that Alderaan would be destroyed, or that he would end up sacrificing himself to help Luke, Leia, and the others escape. It’s possible that Obi-Wan had Luke sell his speeder (2,000 credits) to ‘sweeten the pot’ given the risk that Solo was taking to “avoid Imperial entanglements.” All things considered, you can’t really put a price tag on someone’s life, and given how valuable Leia was to the Rebellion, 15,000 credits was a meager sum for them to pay Han Solo. Still, I wonder, if Princess Leia was worth 17,000 credits, then how much would the Rebellion have paid someone to rescue a captured Mon Mothma?
