A-Body 7.25 BBP Rear Axle - PACIFIC NW
I ship rear ends via the USPS all the time, and it's pretty affordable considering the thing ends up being dropped at your door.
Break the rear apart. The carrier and backing plates go in a large flat rate box. Axles get wrapped in cardboard in one package, and the bare housing gets wrapped and sent in another. I've sent 8.75's this way 2000 miles and the price was way under $200 total.