Try ebay.com, they have a large variety of high quality cosplay wigs.
Hello Cosplay
Hello Cosplay or Amazon
You will need to buy a few things. black wig black long overcoat black Cape(optional) black pants
I'd say pigtails.
buychina Amazon
Most cosplay wigs are meant to act as regular hair..so...yes.
Messy, messy, messy! Black hairspray/dye for the color, and then ruffle the wig with gel.You can see some neat examples if you look up images of 'L Cosplay'.Hope this helps! ^^
You can find a Riversong cosplay wig at various online retailers such as Amazon, eBay, and specialty costume websites like Etsy or CosplayWigs. Additionally, stores that focus on cosplay and anime merchandise may carry similar styles. For a more customized look, consider checking out wig retailers like Arda Wigs or WigIsFashion, where you can find a range of colors and styles to match Riversong's iconic hairstyle.
This is all I can find: http://www.cosplaymagic.com/nashabcowig.html
Try looking up different cosplay sites and ebay.
Are you going to a anime convention? You don't need to cosplay. It's not a must... unless there is a rule for that particular convention.You could just wear a wig and a cute outfit, and say that the character you cosplay would wear this too. Or just wear something similar. You don't have to look exactly like that character.
gotta be L from Death Note. All his costume consists of is a white long-sleeved shirt and blue jeans, along with a messy black wig. Of course, if you have black hair, his hair's no problem.