Some of our collection of D&D cels scans are back online on my sister's webpage, along with scans of the storyboard for Time Lost. URL is member.aol.com/ddrealm

The site came down in part because the scans of the cels were being used to create boxes for bootleged tapes.

There are many D&D cels out there, many fans have them, along with a lot in the hands of the writers and other production staff.

One note of caution, there were some very suspicious D&D model cels on eBay. I can't say more than that, the dealer (no longer on eBay) has treatened to sue any D&D fan who questions the authenticity of the D&D model cels he sold. Since then, some of those model cels have been resold on eBay. 

Then again, there have been a couple absolutely awesome D&D production cels on eBay a while ago. None of which I got :(