Vandersteen's have always kept their value as well or better than most since they don't change that often. They are a top value to begin with (at all price levels), so they are going to always be a good value on the open market.
Companies that come out with a new model or mark whatever every two years hurt their own resale value. Just look up on the site as to what speakers are really selling for and not just listed for and you will see.