Hard to believe that the seller wouldn't bother to learn who drew the cover to this classic issue. Gil Kane is a pretty big name in the original comic art biz. I think he'll get his 30K even if he doesn't seem as motivated to market this piece the way it should...
To answer a q above... I think the artwork for Hulk 181 would actually cross 100K. After all, along with Giant Size X-men 1, that is perhaps the most important cover since Captain America 100 (1968).
If a historically insignificant (though beautiful) Alex Ross cover gets $50k and a standard Byrne X-men cover can get as much as 35K, I can't see a cover like Hulk 181 getting anything less than double that.
JMO