I am no expert in anything, but a DCM in LA was just purchased privately for 4600 by a really savvy collector friend of a friend of mine. Don't know if that effects anything, but also aren't like half of these now owned by members of this forum? Doesn't that fact have an effect on value, since I would assume most of them aren't going anywhere? Not trying to cause a stir, but the person who got it for $3600 seems lucky to me. Maybe I am just jealous!
It all boils down to supply, demand, how quickly you want to see, region of the country and the world. You might get a better price if you sell it locally in a big market. People can see it in person and pay for it in person. It may work in reverse as well.
They look great, play great, and sound great. Worth every penny.