Hi Tom,  If you can get the rolls you want for $7, then you're doing
pretty well.  I've been forced to pay upwards of $15-20 for the Duo-Art
rolls that I want (but then I already have around 300, so I only go for
the ones that I really want).

The Duo-Art Audiographic series are the rolls most desired by
collectors (not to be confused with Ampico's Audiographic series that
are regular rolls).  The leader of a typical Duo-Art roll is perhaps
two feet long, but the leader of the Audiographic series roll is seven
to ten feet long and it's filled with a lot of text telling about the
composer, the interpretation of the piece and the performer.

For example, I have an Audiographic roll of Mendelssohn's Fingal's
Cave Overture; the leader tells about Mendelssohn, his works, and
a description of Fingal's cave, where it is, and a picture.  Then when
the music starts it gives commentary of what they visually felt was
going on in Mendelssohn's mind when he wrote the music with the piece
in mind.

As for the music itself, usually it's identical to a regular Duo-Art
piano roll and the music and expression can be compared with them
hole-for-hole.  I have a roll that is an exception to that as well: it
is played by Josef Hofmann, W254, Introduction and Rondo Capriccioso.
The Rondo is the same as the roll of the same title, but there are
several sections of music defining Mendelssohn's style illustrated by
musical passages.  I don't know for sure if Hofmann played the passages
or if they took them from other rolls, etc.

The Audiographic series are by far the most expensive rolls.  If a
regular Duo-Art roll will sell for $10, then the Audiographic roll
usually goes for $60-100.  I've seen them go for much more than that --
$200 to $300 is not uncommon.  I have a copy of Hofmann playing the
Moonlight Sonata, 1st movement.  The regular roll (non-Audiographic)
sold on eBay for $150, so I can only guess what the Audiographic that
I have is worth.  (Not that I really care as I am not investing in
this, only collecting.)

It's worthwhile to try and get some of these rolls -- they are
interesting.  There are a few different series, however.  There is the
Audiographic "W Series", which are the "world music", trying to give
cultural aspects to the rolls presenting typical music from around the
world.  The "A Series" is the standard Audiographic; the "D Series"
I believe is the British series of the same rolls.  I've seen them with
two rolls from the same performer but different interpretations and
having different numbers.

What makes them rare?  They were released around 1930, trying to promote
the Duo-Art when the industry was already dying, and they were more
expensive when people already were hurt for money.

Good luck!
Eli Shahar