You can pack almost anything securely with just corrugated cardboard, if you know what you're doing.
Many years ago I used to work (in the computer department) for one of the UK's biggest cardboard box manufacturers. One of our biggest collective customers was the Scotch Whiskey industry. Think about it; a case of whiskey contains 12 fragile glass bottles, all of high value, collectively heavy, and completely ruined if anything breaks. They used tri-wall outers, all flaps meet* and interlocked double walled dividers the height of the case between the bottles to protect them from one another. They were some of the most expensive cases we regularly made.
If you want a good case to ship stuff in, go down to your local off-license/liquor store/supermarket and ask for some empty cases that bottles of spirits came in.
*An AFM, or all flaps meet case, is one where the inner and outer flaps that form the 'lid' are exactly half the width of the case, forming a double layer of card the full width of both top and bottom. The flaps meeting each other in the middle gives massive lateral stiffness to the case.