Not really a rare collectors item, as there are a number out there. I believe you are referring to the D2 and D3. Both lights are pretty much a 6P or 9P with pocket clip. I would say a D2 in like new condition would be a good deal at $50. a D3 at $60ish, but this will very per person and condition. Overall, I have found they are worth similar a little more than a 6P and a little less than a 9P. Hope this helps.
-Mike