Although the books have been hugely popular for a number of years and the recent film opened to overall good reviews and box office, there is not yet anything available for purchase in the way of Spiderwick costumes. If you want to try for a group Halloween costume as the Grace siblings, you have to use sweatshirts, jeans and some cleverness with props.
The Lack of Available Spiderwick Costumes
There are several probable reasons for the lack of easily available Spiderwick costumes and props, despite the existence of the film and video game. For one, unlike Harry Potter, Alice in Wonderland, or other popular kids' fiction, the costumes are modern and not particularly evocative. There is nothing distinctive that shows who you are or sets you apart for a costume party. Also, while the books are well-read and loved and the film did respectable business, this is hardly the same thing as being a cult phenomenon, like Harry. For that matter, not all cult phenomenons that take place in a slightly alt universe yield costumes. One need only witness Buffy the Vampire Slayer for confirmation. A hit TV show that spawned a rabid fan base who snapped up action figures, comic books, poster art, soundtracks, DVDs and even a board game, there were never any costumes available, nor did they show up in the Cosplay world or anywhere that other supernatural stories had influence. The costumes took a definite back seat to the stories and characters. And so it seems to be with the Spiderwick Chronicles.
Buying Spiderwick Movie Costumes
If you're a serious fan of the movie, and a collector to boot, you may want to own some actual costumes built or bought by designers Odette Gadoury and Joanna Johnston. Since the only practical way to do so is online, you want to go with a reputable site. Try Premiere Props, which has a wide selection of clothing and props from popular recent movies and occasionally gets some great stuff from older classics. They work in conjunction with eBay and have deals with a number of film studios to sell selected items, each of which comes with a certificate of authenticity, so that you know you have the real thing in hand. They currently have eleven Spiderwick costumes from which to choose, some of them even sporting the original wardrobe tag used on set! There are items such as the burgundy hoodie worn by Freddie Highmore (Jared), the denim jacket worn by Sarah Bolger (Mallory) and the tan jacket and corduroy trouser outfit also worn by Freddie Highmore as twin brother Simon. You can also get adult clothes worn by Mary-Louise Parker (Helen) and Andrew McCarthy (Richard).
Creating Your Own Spiderwick Costumes
If you have identical twins, or two boys who look alike, you can put together simple modern outfits of jeans and sweatshirts to be the Grace twins. Add Mallory, also in jeans and perhaps a long-sleeved T-shirt. But what you really need are props. Since Mallory is an expert fencer, skills called upon more than once in sticky situations, she can carry a sword. Jared can carry a monogrammed key and a book with the title: Spiderwick's Field Guide to Faeries, along with a note that warns him not to read the book. Simon can carry an animal to represent one of his pets. You can try incorporating a crystal ball as well. If you're more interested in being one of the goblins or other faerie creatures, your work is going to be much harder. You may just want to wait and see if rubber masks become available - maybe after the sequel!