Try looking up display companies in the area or booth makers for conventions—-constantly packing and repacking product displays, equipment and the booths themselves which must set up several times a year. They will make special crates for whatever they are shipping and could most likely help out with one they have and are not using or make one to fit.
There is a company called “Penn” that makes fasteners, clasps and parts to make cases like what rock bands use to transport stages, speakers, audio equipment and all with foam inserts, etc….depending on how much you want to spend and how much you are going to use it all, you could call them and get the contact info for someone they supply near you and get a really well made case—-wheels, etc, that you could even sell when you are done——or maybe even rent the actual case for the time you need it.
Craigslist most likely has used band crates or cases for sale too——
Shipping depends more on volume than weight generally so the extra protection would only work out better for you in a heavy duty case.