You can find them for as high as $600 for a hard-shell case or for a soft-shell case, about $300. We’ve had a set of luggage my mother gave us like 10 years ago and I repurposed the largest one to carry my OTA (telescope tube). It’s dimensions were perfect. 13″deep x 18″wide x 28″ tall. I went to a craft store and got some 1.5″ foam, wrapped it in a circle and smushed it into the bag. Then I cut off the excess which left me with enough to do a top and bottom and a sliver to set on the face of the tube after I lay it in there.
I did have to carefully cut a slot and hole in the top piece of foam to make a pathway for the focuser knob on the scope. This is the only thing I really worry about with this setup.
To make it look nicer and more finished, I got about 3 yards of shiny-satiny black soft fabric that I thought would be good to use and stuffed it along all the edges of the foam. I made sure to form the fabric into the slot and hole for the focuser knob. I don’t want that snagging or to have any weight on it at all. There’s no sewing involved, simply tuck in about 1 foot of material around every edge, leaving a long extra piece hanging out the bottom.
Once the tube is set in place, bring this excess fabric up, fold in the sliver of left-over foam and set it on top of the OTA. Then zip up and you are ready to go. The bag has plenty of storage for accessories, although I do not keep my lenses in this bag.
I would like to get a hard-shell case for it, but with the types of luggage available, the hard shell is very thin and I worry that it won’t hold up over time, but something like this looks a little more beefy. I’ve been looking at Ross and TJ Maxx when I happen to go to those stores, but nothing there seems to be big enough.