I think a fair price for a decent EBD is in the $1500-$2000 range. I've searched out and bought two this year and this seems to be the acceptable range.
However, I did score an original 1981 edition is fantastic shape with factory Mylar playfield and scored it for only $2000. I would have gone as high as $2500 for that one. I think anything over that is getting excessive for this title... but that will also vary by geography.