SKB Case for my Brompton is great but I don’t need it and I can’t sell it because of shipping costs. Any advice?

To give some more info: I am in Tucson, Arizona, USA. I got this SKB case for my brompton and it is well made and fits juuust right. BUT it is a bit bulky and heavy for airline travel at 20 pounds. My return window has closed on it, and I figured I could resell it, but everywhere I look the shipping costs are huge. SKB must get a super deal on shipping because I’d likely be paying someone to take it off my hands.

Does anyone know if there are cheaper methods for shipping?

Is anyone interested in a case like this?

Thank you!

20lbs is well under the checked baggage limit, isn’t it?