***
On the other hand they also carry books that are still in print, charging
up to five times what they cost new.

"Malcolm" schreef
I've never seen that disparity, can you give an example?

***
I have seen it, although it does not happen all that often.
* * *

And when you say "they", you are actually referring to 13,500 different
booksellers across the world offering their books in a single
marketplace. Prices are bound to vary depending which country the book
was published in and which country the bookseller is in. At the end of
the day, it is always the buyer that chooses what to spend.

***
Sure, it is a big market place. Certainly it offers opportunities that would
not otherwise be there. Still: buyer, beware!
PvR