When my friend bought her new 6600, she bargained the 3 piece rolling carrier in as part of the deal.
That said, Joann's used to always have carriers - they were around $80 (but couponable). I use it for my Bernina for traveling or storage if I need it out of the way for whatever reason.
The carrier is soft-sided but with support (as stated above).
This one is a bit different from mine, but that was over five years ago.
http://www.joann.com/joann/catalog/p...zprd_02265536a
You can check them out your local Joann's. You just want to make sure it's sturdy, and the handle and wheels aren't crap. ;-) It's always returnable.