Values for many single cards can be derived using multiplier lines.
The idea behind this came from the secondary market's use of multiples on
many common parallel issue cards in the early 1990s. For instance, a one-per
pack Topps Gold parallel card was commonly sold at 6-15 times the price of
the base card for that player.
The same idea is now being applied to many
thinly traded and stable insert cards.
Example: 1997 Score Mark McGwire #187
recently listed for $.75-$2.00. The Reserve Collection parallel is priced
using multiples of the HI book value for the base card and, since Mark McGwire
is an established star player, he would get the "STARS" multiplier line of
"8X to 20X BASIC CARDS." You would simply calculate 8 x $2.00 for a LO book
price of $16 and 20 x $2.00 for the HI book price of $40 on the Reserve
Collection single card. Similarly, McGwire is card #2 in the 1997 Score Blast
Masters insert set. The Blast Masters has a multiplier line of 4x to 10x
which you again would apply to the HI base card value of $2.00 for Mark
McGwire to arrive at the Blast Masters value of $8-$20.
Keep in mind that
there typically will be different multipliers used for rookies in the parallel
or insert sets since the pricing for their base RCs is often so much higher
than that of veteran players. On occasion a "YOUNG STARS" multiplier is used
for players who have not yet established themselves as collected players in
the hobby. These are typically second- or third-year players.