I keep my tube in a wooden box I built specifically for transporting it everywhere. First time I tried putting it in the car I found the speakers on the rear shelf hung down into the boot too far and after getting it into the boot, it got jamed and I couldn't get it out!
So I had to unscrew the lid hinges and take the box out in bits. Now I just use the box to store it in the house with the tripod straddled across it, boxes of other bits sitting behind it. My girlfriend wants me to move it because it looks too much like a coffin....I guess it does!
I have hinted for my birthday that Sirius in Queensland had an ad for a zip up bag for scopes...she would just need to take some measurements and see if they make one to fit. At the moment, I just put the tube in the boot and put a doonah over it and tuck it in a bit. By the time I put all the other bits in the boot, there isn't a lot of room left...need a wagon, or buy back my old Pajero!