The following extends Paul's interesting notes of price variation with
time.

The current price of a shell is of considerable interest to dealers and
buyers.

A number of factors influence prices, and should be taken into
consideration.

Size:  Each species has a range of sizes that usually form a bell shaped
curve when number is plotted versus size.  If you want a shell at either
end of the size range, you should expect higher prices.

Rarity:  Rarity varies with time.  The first shell to be found of a
species is very rare at that time.  When an ideal location for the
species is found, they may be locally common with lower prices.  Some
species experience great variations of populations.  If the species is
found in only a small area, this will effect the price greatly.

Location:  Some species are found almost worldwide, others are found
only in a small area (so far as is known for the species).  Difficult to
reach, small ranges (geographic and depth) will produce higher prices as
they require much greater expense to obtain.
        Some species, though found in a very wide range (such as
Pacific-wide) are rare in some areas (for instance, Cypraea annulus is
not found in Hawaii to my knowledge and Cypraea moneta are fairly rare
today).  If you want a shell that is from an area where is rare, you
should expect prices of a rare shell, and the data and its reliability
determine the price.

Who collects the shells:  Most bulk shells are collected by natives who
earn only a few dollars a day so the prices are apt to be low.  Some
areas only have collectors who normally earn a good wage, and they
aren't apt to sell low price shells.

Data:  The data for shells collected and sold in bulk is apt to be poor
to lacking in detail.  Shells from very different habitats and areas are
apt to be lumped together.  Some may have magnificent data that is made
up in mass and may be worthless for tying a location down further than
to a country. If you expect good data, expect higher prices.

Prices change for a number ofreasons.

--
                     Aloha from Wesley M. Thorsson
Editor of Internet Hawaiian Shell News, a monthly Internet Publication
           122 Waialeale St, Honolulu, HI  96825-2020,  U.S.A
       http://www.hits.net/~hsn   or http://home.att.net/~w.thorsson