I think your local post office or courier service will tell you the exact steps.However since it is a very small item you can just put it in an envelope and mail it like any other letter.I wouldn`t think that you should sign a custom`s declaration form since it is something of low value.Is the jack fully functional?How much would you sell it to me?Send me a PM if you don`t want to go public.
I Have only one jack, I'm not a spare parts dealer =)
Hm...I've never sent any things abroad, so it would be my first experience.
Can you explain me order of my actions, please?