If I have to take a pie somewhere, I use a cardboard box that is bigger than the pie, then I use batting to cushion it so the crust is protected from sliding. You have to get creative on how you mound/pile/wrap the batting, but it works.
I keep the box and batting for re-use. I do the same thing for my slow cooker, so I can transport it with food in it and don't have to worry about it spilling out.