The worse problem to make a cable is to find stuff.
In many small towns it can be hard.

I suppose that if you have a computer you
are able to find this stuff in computers stores of your town.

You can find DB9 in shops of electronic, computers or similars.
If you don't find 3 way shielded wire you can use two times a double wire.
Db9 plastic covering can also be replaced by epoxy.
I made my cable and the total enclosed was about US$ 5.00 (five dollars).
You can use also a mouse connection of 9 pins instead of DB9.
But it will increase costs to US$ 15.00.