Well an unreleased DD does make it a bit more significant, but then again it depends on the game and how popular it was before it was canned, as well as how well it was put together like I said earlier where some companies go and make them professionally rather than just a laser print-out. I don't want you to think that I'm bashing your "what's this worth" thread. Getting a hold of a DD from almost any company is like going into a celebrity's house and stealing their bed sheets. It will have sentimental value (depending on the game) but not worth as much as an unreleased copy of Robotech 64 ;-). BTW, what is the name of the unreleased game's DD you have? Is it Juiced or that other game?
What from Acclaim? Ever wonder why they went bankrupt? Seriously though, I think their value lies more in what it's attached to. If it's written by someone like Myamoto or Sid Myers, and signed by them then it's worth something. If it's written by Joe Bloggs and wasn't even accepted by the publisher then it's worth more as landfill.
I have to agree with Fabrizo, I'd be intereseted in any design docs, released or unreleased. If it for a game you like it would be a great addition to the collection in my opinion.
That reminds me, wasn't Acclaim going to by the rights for RSG and publish it on the Playstation? That would actually make is somewhat probable to have obtained its design doc...