Second that. They're the cheapest way to move heavy stuff long distances I know of. I've received a few things shipped using them.
Pretty fast service. Usually < 7 days from anywhere in the US
You have to drop it off and receiver has to pick it up at one of their depots. That means you both need one somewhere reasonably near by and access to a truck.
If you don't look like a truck driver when you walk in there it's hard to get anybody to talk to you.
- Some (most?) of their places don't take plastic or cash. Money orders only.
- Use the smallest skid you can, even if you have to cut one down. They charge not only by weight but by the 3d footprint of the item.
- Crate your engine. It'll increase the weight, but reduce the chances of it arriving broken.
I have also used Pilot Air. They were more expensive but comparable otherwise.