Many pet stores have ferrets, and there are often ads in the newspaper
placed by small breeders [1.2] with kits to sell or people who want to
sell older ferrets.

A ferret from a ferret shelter is also an excellent choice [1.2].
They're often a little older than kits from a pet store, but they've
probably already been litter- and nip-trained, and the shelter
director will know more about their individual habits and
personalities.  It's also less expensive to adopt from a shelter, and
of course you're giving a home to a ferret in need.  A local ferret
club or a veterinarian who treats a lot of ferrets may be able to help
you find a nearby shelter.

In any case, look for bright, clear eyes, healthy skin and whiskers,
soft coat, and a curious, alert attitude.  You can't tell just how a
kit's colorings will turn out, but if you watch and handle a group for
a while you can tell a surprising amount about their personalities.
Young kits will generally be pretty sleepy and uncoordinated, but
they'll grow out of that soon enough.