In my opinion, you should first go figure out what your cars are worth
(I use the Old Car Price Guide for this) then figure out how much more
than that you would want for them if someone brought a briefcase of cash
to the table.
Calculate in sentimental value, how much you like the car, and your
other financial issues, how rare it is, and what you want in terms of a
future classic car collection. That way, the next time someone says
"I'll give you $XXX" you will be able to know immediately if that's
above or below your prearranged figure.
If someone offered me mucho dinero for the 442...it'd get sold. My
grandfather's Monte Carlo, which I inherited, is not for sale, period,
on the other hand.
-John.