This is the method I've been using for quite a while. It is inexpensive and effective. It works great for one saw or several and does not require lots of packing material. Essentially, the saw is wrapped in several layers of cardboard to provide protection and stiffness to resist damage during shipping.
Since I ship a lot of saws, I purchase boxes from Amazon for about $2 each. It saves me the trouble of finding boxes and saves a lot of time in packing. After all, I'd rather be working on saws than boxing them up.
Step 1: Make a cardboard scabbard for the saw. Mark out a rectangle larger than the saw and cut with shears or a knife.
Step 2: Place the saw inside the fold of the scabbard and secure with packing tape.
Step 3: Cut two additional pieces of cardboard to serve as stiffeners.
Step 4: Place the saw inside of the box between two layers of cardboard and cut the corners down to the height needed.
Step 5: Fold down the sides and trim if needed.
Step 6: Tape securely, affix the postage label, and it is ready to go.