It might be hard to find the same style in different color locally. Look at spirithalloween.com -- they have a wide variety of costumes and wigs for any occasion.
Currently, costume wigs are very popular. They tend to fetch a hefty price on Ebay, especially if they are custom made.
Wigs can be made from a variety of materials including human hair. Typically costume wigs are made from a synthetic material, which could be called plastic. Typically with a costume wig they are cheaper and made from a lower quality material.
Costume wigs that are good quality could be found at light in the box. An other possibility is heaven costumes. Then there are also wigs online and wig warehouse.
To find good costume wigs, I highly recommend going to a costume store. I'm unsure of your location, but many places have stores set up only for fall where they sell costume wigs. A good place on the west coast would be Costume Castle, but any stores such as Wal Mart or K Mart may have a decent selection.
You can find high-quality cosplay wigs for your upcoming costume party at specialty online stores that cater to cosplayers, such as Arda Wigs, Epic Cosplay Wigs, or CosplayBuzz. These stores offer a wide selection of wigs in various styles and colors to suit your character.
You could always consider being a postmodern witch and going with green.
For cheap costume wigs, try www.costumesinc.com orwww.costumes4less.com. Both have great deals and a wide selection of wigs.
There is a store in Tampa that sells wigs. The store store is called the house of make believe and they have all kinds of wigs and costumes avaliable.
The average high quality wig that are used from halloween are actually made from real human hair. These special wigs are designed for realism, and making sure that the costume is of the highest quality.
Some beauty supplies sell wigs. There aren't too many around these days.You can find costume wigs, like afro wigs, tinsel wigs, blode wigs, pink wigs, and all sort of fancy dress wigs at Super Party Wigs.
You can get wigs from a costume shop if you want to, although they may not give you the natural look that you are wanting. Eva Gabor wigs are a great value for the money.
Ebay, cosplay.com, cosplaytrader.com, ads on different sites.