Try abebooks.com.
I looked for a special comic for so long I began to believe it was just a dream. After a forty year search someone suggested abebooks.com. Within a few hours I had three separate, pristine copies ordered, chosen from a list of over fifty avaliable at the time. The price ranged from $3.00 to $100.00.each. Mine were bought for $8.00, $10.00 and $14.00. each.
I have since bought many out of print books, some from late 1800. That may seem old but there are books avaliable there from many centuries ago.