At least one member here used to sell their basses in a hard case, bought for the purpose, which the seller would then send back.
That worked till someone decided to keep it. (Probably an Ebay sale, but still...)
The original Overwater case must be a rarity...
If it was me, I'd be sourcing, and charging the buyer for, a hard case which fits the bass. I guess a generic Tbird case would do?