This article is from the Toys FAQ, by email@example.com (Scott Gordon) with numerous contributions by others.
I want to emphasize that anyone is welcome on this group to discuss
toys or ask questions, but questions about worth or rarity do not
always bring out the best in the group's regulars (but you'll learn
we have a warped sense of humor, at least). If you do ask a
question about worth or rarity, ask politely and in a well written
manner to do as best you can to distinguish yourself from a dealer
(dealers tend to post abrupt and sometimes illiterate queries), but
take the following points (from rtmer TZ) into account before you
ask a question about value, and you may be able to stay out of the
line of fire:
"(A) Virtually no figure released since 1985 is 'rare.' As someone
else noted, two hundred and fifty MILLION Star Wars
figures were produced, so even these aren't 'rare' (since
so many tens of thousands still survive on mint cards).
Most figures produced after 1990 should be considered, in
the scheme of things 'extremely common.'
(B) Any toy produced after 1993 is probably still available on
the toy shelves in stores, the vast majority in large numbers
(i.e. X-Men, Star Trek, Spawn, etc.). Even the figures most
people label 'rare' are still produced in the hundreds of
thousands: Interim Human Torch & Invisible Woman, and
Phoenix, for example.
(C) Realistically, most toys are worth $5-7, i.e. THE RETAIL
PRICE. With a minimum amount of shopping around, you should be
able to find these toys at TRU, K-Mart, Target, or whatever.
(D) IF YOU WALK INTO A STORE AND SEE TEN COPIES OF A FIGURE
'YOU'RE FRIEND'S BROTHER'S SISTER'S COUSIN' TOLD YOU
MIGHT BE 'WORTH SOMETHING,' YOU SHOULD PROBABLY LEAVE THEM
THERE. They are most likely NOT worth very much more than
retail, unless you have some supply set-up worked out with
your local toy scalper.
(E) Just because you see a dealer selling Professor X figures
for $10 each, or even Killer Croc's for $20, doesn't mean
they're 'WORTH SOMETHING.' (God, I loathe that phrase...).
Likewise, because a price guide lists a relatively common
figure for $15 (like Medieval Spawn repaints), doesn't mean
it's automatically 'WORTH' that much. Since the guides only
track the secondary market (dealer/scalpers), even if only two
M. Spawns were sold at that price last month, the price is
marked at $15. Meantime, 50,000 people probably bought that
damn toy at retail at the local Wal-Mart.
(F) Finally, as with all newsgroups, IT IS EXTREMELY IRRITATING TO
MANY REGULAR READERS AND POSTERS TO HAVE BASIC QUESTIONS ASKED
OVER AND OVER AND OVER AGAIN. If you want to find out how
much a figure is 'worth,' try this:
(1) If it's pre-1985, look in a price guide, subtract
about 25% from the amount listed, and you have a
'reasonable' range of prices at which it can be sold
(full guide price plus or minus 25%, with lower-end values
probably more realistic.)
(2) If it's post-1985, it's probably 'worth' (maximum) no more
than $15 mint-on-card. If it's post 1990, it's probably
worth no more than $10-15.
(3) If it's post-1993, it's probably can be found at retail,
and is 'worth' that, unless you pay scalper prices, at
which point it is 'worth' $10-15 for a more common
figure, and anywhere from $15-30 for 'hot' figures. The
latter price will probably drop down to $10-15 as soon as
people realize that speculator frenzy rather than an actual
limited supply is driving prices up; this usually takes
about 2-3 months to sink in to the denser and/or more
impatient heads in the hobby.
(4) REMEMBER THE VAST MAJORITY OF TOYS, NOBODY WANTS AND CAN BE
HAD VERY VERY CHEAPLY IF YOU ARE A SMART SHOPPER.
(5) READ THE FAQ."