I have a 32" flight case that I easily put 3 gongs in (32/28/26 or 24). It protects them well. In fact, it went down a flight of stairs with no damage to the Gongs. As you can imagine, it's a heavy beast when fully loaded. Not for the faint of heart!
You can also get a Humes & Berg molded Enduro case up to 32". These are great and a lot lighter than the flight case, so cheaper to ship.
One question is how much travel will you do? If it's a lot of going back and forth to the same places/areas, it might be more cost effective in the long run to have multiple Gong set ups, one in each place/area (like one in Hawaii, one in Mexico, etc.). Those shipping charges can add up over time. Also, there's no chance of damage from shipping things.