There are some things to consider before buying any herp.  Remember, first,
that buying the animal itself is likely to be the *cheapest* part of the
process; that $20 iguana will cost closer to $250 when equipped with housing,
a substrate, furnishings, lighting, heating, food, and initial veterinary
care.  Second, many herps are sold as juveniles and will be many times larger
at adulthood than at purchase; consider whether you are prepared to provide
suitable enclosures as the animal grows, and just where you're going to put
those enclosures.  Third, many lizards, and all frogs and snakes, are
carnivores; to keep one, you will need to provide other animals as food
items, possibly killing them yourself (see question 7.3).  Fourth, even
vegetarian herps have specialized needs; lettuce is *not* a suitable diet for
an iguana or other vegetarian lizard, and you are likely to have some strange
conversations about turnip greens with your produce manager.

When a herp (or other pet) is being entrusted to a child, there's also the
issue of responsibility.  Many herps require relatively little care to do
well, but this ease of maintenance actually makes neglect easier; after not
feeding the frogs for three or four days, it's easy to forget for another
week or two.  In addition, certain large or flashy herps have a surface
appeal that may draw people (and especially young people) for the wrong
reasons: "If I had a *really* *big* snake, I could scare the heck outta my
friends!"

Let's assume that the kid is responsible enough to take care of a pet, and
that its reasons for wanting a reptile are good reasons.  In this case, the
species described in the answer to question 8.1 are good places to start
looking.  The large snakes, however, are particularly contraindicated in
households with small children; incidents in which a snake injures a human
are *extremely* rare, but the effect on the public image of herpkeeping and
the potential for tragedy are great enough that it's better to play it safe.
For obvious reasons, venomous herps should never be kept in households with
children.

Many, probably most, herpers started as children, and strongly encourage the
fostering of a child's interest in herps and other animals.  This answer is
not intended to discourage children from keeping herps, but to suggest the
most responsible and rewarding routes to that end.