This one came and went, presumably to an, err, off-line sale, in e-Bay (no to me, by the way).
Cerebus #300 p2
eBay item number: 320919603697
You might recall that Dave and Ger agreed to sell me page 20 from issue 299 and page 1 from issue 300, and I picked those babies up on my birthday, back in 2004. I reserved the page from 300 sight-unseen. And then I asked them to do a "What happened between issues 299 and 300?" panel, which was also quite terrific (the POV shifts as Cerebus raises his right arm).
And yes, I saw the plea at the Kickstarter Project for super-scans of original art pages. And no, I am not going to oblige. Sorry.
Some are a cannot-do (they are framed):
One has been drawn on and colored (by the creators), which originally gave me the whole "Get Ger to add art to previous drawings" idea:
And the rest (nearly 150 pages, I guess) are neatly stored and stored away, distributed among lots-o-other original art in the Alchemist57 Great Hermetic Fortress of Solitude, guarded by a Weisshauptian canon (sic). And unless you have a big-ass scanner you cannot do a full page at once in the first place. I'd need to run a Kickstarter project in order to get this done.