Rob...you might try and just take todays prices and "back down" into a
2002 price by utilizing the govt published rates of inflation over the
years...that would give you the value of a dollar in any selected,
historical year...it ain't perfect, but it is quick and "defendable"...

by 2004, the remaining drop in value for 240, 740, and 940 had probably
gotten pretty small.  (in fact, i sold my '91 240 last year for more than I
paid for it in 2000).  maybe $1,000 - $1,500 less than current value.  and,
with continued good maintenance, a '94 940 will continue to hold its value
for another 5 years or so.  along with the 960, it's the last of the RWD
volvos.