I don't think that eBay or other online auction sites are a bad thing
for historical documents.  If I were to run across some old document in
an old player piano, I'd personally have no interest in it beyond it's
curiosity value.  Without eBay (and MMD) I'd throw it away.  WITH MMD,
I'd post and ask if anyone here wanted it.  But if I were Joe Blow who
just happened to open a piano and find it, I'd toss it out with the
dust bunnies, toothpicks, etc. that collect there.

With eBay, good old Joe Blow might think, "Hey, why not try to sell
this, and see what it's worth?"  And so, it survives, sold to the
highest bidder, who after spending lots of money on it, is more likely
to take good care of it.

As for historical information value, as long as there are no copyright
problems, hopefully the purchaser would be willing to photocopy or scan
the document for those who might be interested.

Bill Mackin