Any old container with decent ventilation. A cardboard box works fine--just punch holes in it. Best for the container to be small so there's less room for them to slide around and they stay warmer that way too. You can also just use a box with an open top, if there's someone to hold the box and keep an eye on them, then no need to punch holes in it.
Most important: Line the bottom of the box with something non-slippery like straw, wood shavings, old towel, etc. DO NOT use newspaper in the bottom or leave them on a bare floor. Sliding around can cause permanent damage to their little legs.
Other than that, they're pretty easy to transport.
Enjoy!!!