haze's numbers sound pretty close to me, if its a custom G10 '8 with ZBG blade imho it would be worth ~ $800 to $1K tops, you see a lot more of the G10 '8s vs the ti/micarta ones, IIRC most (if not all?) of the ti/mic ones are waved too, while very few if any of the G10 ones are waved, i dont recall ever seeing one anyway.
as far as interest sure all emerson customs have some collector interest, i dont think any of them will bring the kinda dollar they would say 5 yrs ago, i can remember when a custom '6 could bring $1500, even $1800 or more, they just wont bring that kinda dollar at this time.
and imho he has made more custom '8s than any of them so they arent as desireable as say a '6 or '13.
i saw a G10 '8 (std grind, no wave) sell for IIRC $700 last summer, certainly the cheapest (if ya can say $700 for a knife is "cheap" lol)emerson custom i have seen, like i said he's made a lotta '8s.
8-10 yrs ago ya wouldnt ever see any of them going for less than $1200 or so.