I just bought a rear bumper from a .net member. He shipped it from MA to GA via FedEx ground or freight for about $30 I think. He wrapped it in a bunch of bubble wrap, with that cling wrap stuff around that, and then tape around that. It showed up unharmed.
I wouldn't even entertain letting UPS get their hands on a bumper without plenty of insurance. They tend to break things and then blame it on your packaging.
And whoever you use, plaster giant fragile stickers all over the thing. And hurry up and ship it before it gets too cold out, I think the urethane gets more brittle in the cold.