Wig Places:
eBay - Cosplaywig on eBay
I have bought five wigs from them, including the Lightning wig I'm wearing in my signature picture. Their fibers are usually a smooth but not silky soft grade because they have heat resistant wigs. The fibers photograph nicely and do not get brassy and they are comfortable to wear. The interior wig cap is about 22-24inches I'd say.
Arda Wigs
If a wig you like from Arda says out of stock or sold out, just check their
restock page frequently to see when it will be coming back in stock.
Arda Wigs is like, a Go-To every cosplayer has heard of them and most cosplayers have bought from them sort of company. They have good customer service, pretty good wig styles to choose from, a gallery full of customer photos wearing their wigs, and they're just pretty much rather fabulous. I have not bought a wig from them YET but I really do want to. Their wigs are all pretty much at least $30 though, but you buy quality, reliability, brand name, and thickness. Arda Wigs are known for great wig fiber thickness and their wig cap sizes can accommodate larger heads or cosplayers who have a lot of hair to cover up.
Gothic Lolita Wigs
I just adore GLW wigs, the quality and colors are lovely and they're for daily use so pretty much everyone adores how soft and pretty they are. I haven't bought any yet because they're pricey and the ones I want are currently out of stock and no note on when they'll be back :s
MatchWigs
Fairly new wig seller, but they have good prices and a somewhat varied selection. They are incredibly friendly and they put up new wigs fairly often so it's good to check back every so often. I'd like to order from them at some time in the future so I can see for myself their quality but they use the same fibers as Arda Wigs so they're quite safe.
eBay - greatarchy09
I bought the Long wave 90cm pink cosplay wig from this seller and the quality is really pretty, I loved the style of the bangs, the wig cap fit very nicely, but the fibers are not silky soft. Comfortable and cute but also heat resistant so a little stiffer.
eBay - kasou06308
Wigs are pricy but the seller is extremely personable and fabulous with communication. You pretty much get the wig as pictured. If you want a style and color you can't quite find elsewhere but she sells one just how you need, the price is pretty much worth it.
Epic Cosplay
US based wig site. They have a wide selection but I've not ordered from them before...Personally I think they're a little too expensive and I don't like the mannequin heads they use or their site layout and stock photos so I just tend to avoid them, but there are a good number of regulars in the cosplay forum that swear by Epic's quality. Not to mention super fast shipping since they're local (sorry if you're not in the US, I tend to just assume people are in the US <xD)