Inspired by a post on Miss Celie's Pants, I felt compelled to write about "wigan". I then checked Kathleen's Fashion Incubator blog who offers far more information on the subject than anyone ever even asked for (which is one of the reasons I adore her), and then referred to my own sewing definition and explanation bible, otherwise known as Claire Shaeffer's Fabric Sewing Guide.
Wigan is sold by the yard, cut from a roll of stiff, bias cut interfacing, somewhere around 1.5" wide, and used for hems and cuffs.
Looks like the best garment district alternative, if you cannot find it pre-made, would be to bias-cut it yourself, using horsehair interfacing from Steinlauf and Stoller, (doesn't sound like a terrible amount of effort - personally, I'd use the continuous bias method to make yourself a reasonable amount. That's not hard at all...
|Example of how to do this is found on The Sewing Loft Blog|
Otherwise, Banasch's has been rumored to have it, if you call and mail order!