I think the Reward is minor Compared to cost of slave and training her.  I do enjoy the game so I guess it's up to you to decide what the rewards should be for all of this for free so i'll quit harping

The quest is far from over yet. ;) Just wait for phase three, when the MC gets to attack the palace.

Then there's also the post-installation rewards (after, and if, Aria rises to power).

I sold her...then went to previous save. saving up my millions 20,000 a day so i can get to phase 2...might be a while huh