I have friends, a couple, who are both severely allergic to most cats.
They would adopt if it were practical, but their allergies go nuts the
second they even walk into a shelter.

They researched the reportedly less-allergenic breeds and visited with
two Siberian breeders and one Devon Rex breeder in their area
(Washington DC Metro).  It turns out that they are only mildly allergic
to both of those breeds, but they didn't like the Rexes because most of
the animals they saw had health problems.  They didn't like one of the
Siberian breeders because most of her cats seemed to be frightened of
people, or at least not very friendly, and the conditions in the house
seemed unsanitary.

They really liked the other Siberian breeder and purchased a kitten
from her.  He is sweet, friendly, healthy... a great cat, and they want
to get a second cat to keep him company, and because they just really
love the first one :)  Unfortunately, the breeder is not expecting to
have another litter of kittens for at least six months.  By that time,
kitten #1 will be over a year old, and my friends would rather
introduce him to a new cat as soon as possible.

Siberians are fairly rare, and they'd like to avoid driving all over
the country to interview breeders.

Can anyone recommend a good, professional breeder  on the US East Coast
with well cared-for, well-socialized cats who may have kittens
available in less than six months?

TIA

--
Jennifer