For a one-time use, just get a box from your local bike shop. I've done that quite a bit and never had a problem. There's lots of info online how to pack the bike.
I have a Pika soft case and it works well. The wheels, in padded pockets, protect the frame which is also well padded - I just pad everything with foam pipe insulation fixed with blue masking tape. So far so good.
I've used hard shell cases and they're a PITA to transport and stow when you get to your destination. The Pika is easier, and much lighter, to deal with.