i did the ebay thing-
i had a laptop that would boot, all the way to the desktop, but was really really slow.
plus it was a few years old.
i booted it up, and took pics of the laptop with desktop visible to show it was working, plus showed the two docking stations I had for it, then totally described problem: very slow, plus gave all specs (ram, chip, hd, wondows version).
i sold it for around $80 on ebay.
there are enthusiasts out there who will know the laptop, and will bid for it either because they believe they can get it working well, or will scavange it for parts.
so, just show it as best as you can, and auction it off.
main thing: be honest. that is what i did with mine, and I got great feedback fro mthe buyer for a laptop that would hardly do anything after booting. He / She totally knew what they were getting.
for all I know, they simply wanted the docking stations. But that is not my problem.