Well, when I sold my last two basses, they were shipped differently.
The first bass didn't sell with a hardshell case, only a gig bag. So I made a box out of wood and shipped it that way. I put the bass in it, put bubble wrap all inside and then screwed the top section on. I guess it got there okay.
The second one had a hardshell case, so I used cardboard.......I mean corrugated sheets and wrapped it all around it, taped it up the best I could and shipped it that way. I also wrapped up the stand that went with it in bubble wrap and boxed that up the best I could.
Make due with whatever you think will work well, and with what you have access too.