It costs that much because there is a minimum crate size for live animals, so there really isn't less space. The only time anyone actually ships rats is when, for example, a group of breeders on the east coast get together to expand their blood lines and get a group of rats from the west coast. 8 or 10 rats can ship "comfortably" in the minimum crate, so the cost isn't nearly as much when a group of people are splitting it.

You rarely see any of this, though. Most of the time, to get a rat from point A to point B, you arrange a "rat train" with owners/breeders that are headed that direction. Some of my rats got to me via "in-betweens." For instance, a breeder in Columbus picked up a rat for me when getting her own rats from a breeder in Toledo. Then I drove to Columbus to pick him up. Cut my driving time in half and was no extra burden on her.