No "cosplay" commissioners I can recommend but I can reccomend some wig sellers:
Amphigory; these used to offer international shipping but now they don't which makes me very sad. You CAN order through Katie Bair though, but she does add commission, so only resort to Amphigory if need be. In any case, these are hit and miss, some good and some bad; they're all different companies, but they are divided by quality on the site which helps. I got the most gorgeous wig from here a long time ago, though, I wish I had an excuse to wear it more often!
As with Cosworx, I'd only use these if you *have* to. It's difficult to order, expensive to order and their offerings are pretty much the same as Cosworx anyway, besides a few exclusives (my Yayoi "Luna" wig being one. Oh man. Love that wig so much).
My examples: my Yayoi (modified) & Mithos wigs are from here.
Cosplaywig; great quality wigs, usually nice and thick and easy to style. I love these because they offer pigtail wigs, custom character wigs, a wide variety of natural colours as well as party ones, etc. They have great choice all the time, usually, unless they haven't restocked recently. Some great exclusive colours and mixes too. Only thing that bugs me is a) have to pay for shipping (whereas most other chinese sellers are free worldwide) and b) expensive prices; I know the value of £GBP has dropped lately, but they have increased their prices too. That said, I think every company has been lately...
My examples: my Alice, Taruto (modified) and Vyse wigs are from here.
Cosworx; good quality (for the most part), good choice (for the most part), good cosplay wig supplies. I usually only use Cosworx is nowhere else has what I need in stock. Their prices are expensive, their shipping is expensive, and while I've personally not experienced any problems, they can have long delays on shipping & processing which means a wig might not get out on time for the convention if you're ordering too close to the event, or if they send you the wrong one (which has happened!!), they have been reported to be slow responding.
The biggest issue is that they offer so many natural wigs and so few party ones in the right colours. If you're looking for natural wigs, this is the place to go, really, but leave party colours to other sellers unless you're desperate for a colour or style they have. That, and the wigs they offer are all from different companies. I've bought from them numerous times and had no issues (beside one wig being kinda brittle), but a friend bought a wig that was terrible. I suppose it's hit and miss as to what you buy, but I've found it's best to look up reviews for wigs on cosplay.com or via google to see exactly what you're buying and whether it's any good. I think cosworx actually post their own threads for their exclusive wigs, which is nice, and they answer questions on the forum (or at least they used to - not sure about now).
My examples: my Kaoru and Azuma wigs are from here.
Professionalonly; the only gripe I have about these really is that the quality a) isn't as good as other sellers and b) their photos rarely look like the wig you get. They look similar, but they're not exact to what you recieve. Some of them are either badly photographed OR in awful condition from what I can tell, especially on the custom character wigs like Sakura from Naruto or Edward Elric from FMA. (seriously, go look them up.)
They DO offer free shipping though on most wigs, and their prices are very reasonable for what you get. They don't have as big a party colour selection as some places though but they do have a lot of natural coloured wigs.
My examples: my Parin (modified) wig is from here. I bought two of the long copper wigs for my Parin wig and botched them together. The wefts came out easily and transferred easily to make a nice, thick, soft, lovely wig but the number of wefts was definately lower than in wigs from elsewhere. The original wigs were very thin. The photos of my Parin wig show off how thin it is, but keep in mind, it *is* braided, so it appears much thinner than it actually was. That thing was heavy when the two wigs were sewn together.
Wigfashion; my new favourite place to shop for wigs, lol, this shop has a great variety of wigs at pretty cheap prices, and with free shipping!! They have an excellent variety of natural and party colours, oodles of styles, wefts for sale.. you name it, they usually have it, or you can at least work with it as a base for a custom wig. The quality is pretty good too; I'd say they're a little thicker than professionalonly wigs, but not as thick as wigs from cosworx or cosplaywig. Their short wigs are the BEST though! I love them. They're really comfy and look great; not thin at all, well styled, and a great selection for those who can't style wigs themselves. All of their wigs are lovely and soft, too.
The only gripe for these is that they don't have "custom" wigs, but with the number of wig styles available and the price of them, it's cheap enough to modify them and make them up yourself if you have the know-how and the incentive. That and one of the wigs I bought, while it has a skin-top, has a little hard, plasticcy, nubbinny bit at the top where the wefts connect from the centre. It's bizarre o_O
My examples: my Luke & Liechtenstein wigs are from here. (Liechtenstein is the wig with the nubbinny top bit) Though when I was adding the ribbon to Liechtenstein, I found the quality was great; even though I tied some of the hair to the side, you couldn't see the wefts or skin top at all underneath.
...I hope this helps? ^^; just a few of my experiences. I'm not right, of course not, but hopefully this can help some people when deciding where to shop for wigs. Make sure you have a good long look around - wait a few days, too - see if places restock. You can get great wigs at cheaper prices if you wait and see what comes up elsewhere and just keep checking around a few shops.
Also keep in mind that for some companies I do have longer and shorter wigs than the ones given as examples, I just don't have any photos up on CosplayIsland of them yet. (e.g. I have a long wig from wigfashion I have a short one from professionalonly etc..)