I have had very good luck, in the past, purchasing piano rolls on
eBay.  Generally I only buy rolls that have an accompanying picture
and description.  Often the quality of the pictures is good enough to
see the condition of the boxes, and some sellers will have a picture
displaying the roll partially unrolled out of the box, so you can see
the condition of the leader, collars, and sides.

If there is any question in my mind about condition, I always will
write the seller asking for particulars about condition, especially
if the seller states they are unfamiliar with the product.

Ask if the rolls appear to be attic-baked and brittle, or been stored
in a damp area and show signs of mold.  Ask if any of the rolls have
metal collars that are rusty, if boxes or paper have water stains.
Ask if rolls have cracked or missing collars, have any obvious large
rips, and if boxes are intact. Ask for more pictures, if appropriate.

I have bought a few collections of rolls, in spite of them being in
fairly bad condition, with the idea that I would use them just for
scanning to MIDI files, so it wasn't a huge problem if they were not
perfect.  However, I would not pay more than a couple bucks for really
poor condition rolls, as most are not fit for more than a couple of uses
and may require quite a bit of repair before they can be used at all.

When purchasing for primary use on a player piano, it is best to avoid
badly deteriorated rolls, as brittle rolls shed much paper into your
control tubing causing no end of problems.  Moldy rolls introduce
paper, mold spores and sometimes bugs into your system.  Both type
rolls are going to be distorted and difficult to track properly.  This
can also lead to paper shredding on rewind.

Unless there is a particular roll in a collection that you "must have
right now at all costs," I suggest you do not bid more than a couple
bucks per roll, tops, for poorer quality rolls and maybe up to five
bucks per roll for good quality rolls.

Tom Lear
San Francisco, CA