Storage boxes. Can I discard high end shipping boxes, and still sell in the future?

I recently bought a nice used pre-amp and although it arrived in great shape, it was not the original box. I spoke with the manufacturer, who is an excellent human, to order an original box in case I moved or needed service, etc. He informed me that he pays $200 per shipping box. He laughed and noted it is a custom sized box, but otherwise was mostly 8 foam corners. Says his price (he does not mark-up his resale price) has skyrocketed recently. He recommended I keep box it was shipped in with the molded foam and not spent the $200.

You cannot ship insured without the original boxes. I’ve seen manufacturers charge $400 for a replacement box.

I buy nothing without all boxes,packing,paperwork etc...too many used pieces with it to deal with incomplete units

"You cannot ship insured without the original boxes. I’ve seen manufacturers charge $400 for a replacement box."

Say what? Where did you get that information from? I've bought and sold gear many times without original boxes and always insured!