Ply wood is stronger than MDF and weighs less. Build it like a sub box with a support for the motor and recess the baffle into the box enough that you can screw a top on it to cover the cone. Brace the corners the full heighe of hte box. Ship it via freight shipping and make sure it is labeled "HEAVY" and "FRAGILE." The freight guys will be better equipped to handle a heavy crate IMO and less likely to drop it. Make sure it is insured either way.
Wrapping it in newspaper won't meet the criteria for "adequately packed" for something that heavy and thus wouldn't be insurable.