There's an article here for making foam crates
http://www.airfieldmodels.com/inform...ates/index.htm
The author ships via the post office. He is a custom plane builder. He charges $40 to $50 for crating and says insured shipping is $55 to $75.
Greyhound will ship crates in the luggage compartment of buses. I've heard that it's cheaper than the post office. You have to drop it off at the bus station, and the recipient has to pick it up at the station on the other end.