(1) You can always adopt a bat in your gothling's name. I know I posted this previously but you can always go to Batworld Sanctuary by clicking here for more details. For fellow Canadians, you can also adopt a bat though the Canadian Wildlife Foundation. where you can name a bat, get a stuffed animal, info about bats and white nose syndrome.
(2) Go to itunes or your local Cd shop and buy some goth classics such as: The Sisters of Mercy, Bauhaus, Siouxsie and The Banshees, Joy Division, The Cure. You can also get goth compilation CDs. Those were great when I was young and new to the goth scene (before the Internet days!) as it introduced me to some new bands.
(3) Anything Nightmare Before Christmas related.
(4) A skull mug. Even better, add some loose tea with it - which leads to.....
(5) Want a loose tea idea? I thought this Edgar Allan Poe tea was pretty neat, sold here on Etsy
(6) Why not a book? I suggest Gothic Charm School by Jillian Venters, The Goth Bible by Nancy Kilpatrick, The Vampire Chronicles by Anne Rice to name a few. I am also very fond of Holly Black especially her Modern Faerie Tales series. If your little Darkling likes comics, Roman Dirge (Lenore) James O'Barr (The Crow) and Neil Gaiman (Sandman) are good. You might want to make sure the little gothling doesn't have these books already in his/hers bookshelf, though.
(7) Good Goth has some pretty neat soaps, perfumes, scented oils, etc. Check it out here
(8) Black candles, can't go wrong!
(9) Black nail polish, can't go wrong!
(10) Anything that has bats, monsters, horror related would also make a pretty cool gift. The Occasional bat has some really cute items.
(11) The Crow, lets be honest if your gothling doesn't own a copy of this movie or anything related to it, you need to buy them some!
(12) A pale cover up or foundation such as Stargazer or Manic Panic Goth white.
(13) Black lipstick!