Zane Grey

Bob -- a WHOLE lot of the answer depends on four particulars about the entire group. Are they in -- not decent condition --
but in EXCELLENT condition?

Which particular titles ARE they?
and what are the LATEST/ newest and the EARLIEST print dates??

one other thing -- IF any of them have ANY phrase along the lines of Book Club or Editions /Series... that is -- surprisingly, to most people -- a Bad Thing if you want to appeal to those who are collecting for literature/ antiquarian values ....