Okay so I was watching that SNL skit where Mark Hamill is sold on the home shopping network and it gave me the idea.

Han like gets a tip and goes to an auction of some sort, maybe he had just finished a job, had extra credits to spend and heard they had some good stuff. So he goes there and things seem pretty normal and they do have some interesting stuff being sold.

Then they bring out Luke.

Han is like "wtf" because he wasn't expecting them to do that kind of auction (and Han does not approve).

Han has no interest in "owning" a person, but he's watching Luke, who looks very lost and scared, and the auctioneer saying what he could be used for isn't helping make Han any less pissed off.

So Han decides to try and buy Luke to help him.

Then either he wins Luke or someone really asshole-ish wins Luke and Han just.. "yeah, no." and rescues him.

Though Han tells him he's free to do what he likes he chooses to stay with Han (maybe his aunt and uncle still got killed but he got captured before he could get to Ben).

Or in the event of Han having "stole" him, they gotta get off the planet quickly.

Skysolo ensues.