I am interested in this thread because I was hoping for some travel cage ideas also. I don't have any experience with the cage you posted but since it says it's flimsy I would be afraid it could fold or bend during transport and the babies could get loose.
One idea I had was to make a PVC cage, but make each panel separate. So when I use it I have to zip tie the sides, front, back, top, and bottom together. That way when it isn't in use I can unzip-tie and store it flat (under a bed).
Let us know what you choose, I might like your idea better:)