If you don't know where to get it, and you haven't been keeping herps
long
enough to find a source, are you sure you want one?  Hard-to-find
species
are often hard to find precisely because they're very difficult to keep,
and
should only be essayed by very experienced keepers.

Assuming you really do want whatever-it-is, there are a number of large
commercial dealers who are good places to look.  A good starting point
is
the breeder/mail-order FAQ, available on Liza Daly's WWW page, at the
URL
        <http://fovea.retina.net/~gecko/herps/misc/breeder-faq.html>

Many large herp dealers and prominent breeders advertise in the pages of
herp magazines like the ones listed in question 5.2.  Local herp
societies
are also a good source of pointers, since many of them have members who
attend conventions regularly and stay abreast of others' breeding
projects.

For the record, this FAQ *strongly* discourages the keeping of venomous
reptiles by any amateurs but the most expert and cautious.  Many
venomous
snakes are extremely attractive and have a powerful appeal; however, the
dangers of keeping "hot" animals are very substantial, to say nothing of
the public-relations disaster and potential tragedy that could result
from
an escaped animal.  (And there is *always* a chance of escape; what if
there
were an earthquake and all your tanks were shattered?)  The prudent
route is
to leave the venomous critters to the wild and the zoo, and go there
when you
feel the urge to admire them.