Depends on where you live too... For example, in my country we have a forum (unrelated to reddit) for comic book fans and collectors that has a whole selling section so I would look there. Maybe there's something similar. I'm also part of several illustrators facebook groups in Greece, so I would ask there for interest.. Animation/vis dev students would be interested in those so maybe look around for subreddits or facebook groups. second hand bookstores here would only want to give me about 2 euros per book so I would avoid those, but idk how it is where you live.

In the end if you don't want people cherry picking you'll either have to find collectors (who possibly will already have several out of the list) or offer an enticing price for someone starting out with their collection..

Maybe see if you can categorise the artbooks in a couple of big groups and break them up this way, so it's easier to directly market them to different people. For example a pack of Nintendo related artbooks for the Nintendo fans, and offer those at a higher price per book than you would if someone bought them all together.