I personally would never expect any kind of financial compensation for online conversation, though it might feel a bit strange if an entire thread was reproduced verbatim (but you already said you were avoiding that route). If it were me, I would try to credit by name the people I felt influenced my thoughts in connection to the specific places they were influential.

You might also consider something like a free copy for some participants, as that seems like an appropriate (if still above and beyond the call of duty) token of gratitude and also avoids the minefield of framing anything as payment for use of intellectual property.

Side note, I clicked the PDF option in the poll above, but if the artifact was an attractive and nicely bound book rather than glue-bound POD thing I could see myself backing for that (or buying it later). I’ve mostly sworn off cheap POD printed matter except for the occasional zine-type thing.