Check the DtD website for pre-publication specials.
Sometimes they have good prices, sometimes less expensive elsewhere.

A comment about ethnic music in America, which is seems not a high priority among mudcater or the folk community in general.
An Lp issued in 1965 seems to have had little notice - issued by the University of Iowa press presented an overview of the recordings made by Dr. Harry Oster of these subcultures (Folk Voices of Iowa).
[Harry Oster is well known for the series of LPs issued under the Louisiana Folklore Society and Folk-Lyric logos. Many of those albums reissued by Arhoolie Records.]
There are many recordings available of World Music - well represented in the Ethic Folkways catalog, Arhoolie reissued 78's of central-European groups, and Yahoo's Secret Museum of Mankind, but
I'm not aware of much documentation of these groups traditions in America.
I'd be interested in what other LP/CDs document these musics in America.
Best wishes, Thomas.