Brown throats as a group are not common in aviculture. There are
several breeders that are trying to establish breeding stock from the
birds that were brought in about 8-10 years ago and their offspring.
True St. Thomas' are EXPENSIVE. Many sell Brown throats (which the St.
Thomas is the nominate group) as St. Thomas.
Thomas Arndt's book "The Atlas of Conures" (T.F.H. 1993) has several
great pictures of this bird as well as of some of the recognized
sub-species (there are 11). If you are interested in conures this is
the book to get. I has wonderful pictures and drawings of both
Aratingas and Pyrrhuras.
Natalie