Their value would be in what condition they're in, if they're decorative vs just plain, how old they might be, and what someone is willing to pay. Pocket doors are still being used today, made new.

Pocket doors have been in use since the 1850s.

And if one is an old house lover, the value of the home is increased if the pocket doors are functioning and in place.

The older pocket doors ran on tracts on the floor & had roller/wheels mortised into the bottom of the doors; later ones are suspended by pulleys attached to the top inside of the door framing.

In my area (central Atlantic) the older, larger door sets with the bottom rollers intact bring high dollar because they're scarce whereas the smaller doors on pulleys are plentiful & cheaper unless there is something special about them. The problem is finding someone who needs matching doors the exact size as the ones you have for sale.

The pocket doors in my Mother's house are massive.

There are 4, two singles and one double.

Each one is made of clear American Chestnut and is larger than a 4x8 sheet of plywood.

Try calling a salvage yard to see what they'd pay for them.