Putting this costume together was difficult; as many Alice Cullen cosplayers are sure to know, the dress Ashley Greene wears in Twilight is very expensive. It took me a while to find all of the most important pieces, so I thought I'd help out anyone who aspires to put this look together.
Choker: I hate the Hot Topic Alice necklace, so I went to Etsy.com for a custom made one. The advantage of getting a custom choker is that you can have it sized to fit you perfectly -- the Hot Topic ones are huge! I got mine from AmeliaColette on Etsy: www.etsy.com/shop.php?user_id=…
Hair: I used my real hair, which has been cut in the Alice Cullen style for quite some time. I achieve the flipped look by separating my hair into layers, flipping them slightly with a flat iron, and hair spraying everything like crazy. Taking a picture of Ashley Greene as Alice to your stylist will probably yield the best results.
Dress: The dress is Oleada by Diane von Furstenberg and it has become nearly impossible to find -- especially at a reasonable price. I actually got mine off the cosplay.com marketplace. This dress tends to run a little big, and if you come across a size that's too big for you, grab it anyway -- it's easy to resize. The size 8 dress I bought became the smaller size necessary for me to wear it with little difficulty.
Shrug: Finding a black, long sleeved shrug with the same cut out design as Alice's in the movie was difficult. I couldn't find the exact one, but I found one close enough for my liking on Ebay.