why it's reasonable to charge people who
contribute to the show more
than those who just turn up to view.
Compare this with academic publishing: in most cases authors are charged
an amount $50 or more per page, and the issue itself (while not cheap)
is sold to subscribing members/libraries for far less.
Just like academic publishing, old computer exhibitions are not generally
show biz.
And usually the exhibition price is a lot smaller than the money/effort/
time involved (just like academic authorship.)
Admittedly usually academic authors use grant money to pay the author
fees.
Tim.