It's sad and disgusting, but the scammers prey on impulsive buyers and what I call "emotional" purchases.
In case your dad doesn't believe us or you about authenticity, please inform him that Gene passed in October of 1991. VI opened in December of 1991. If any of these posters were out in the hands of collectors before the film premiere, it certainly would not be this design. I believe the original release poster was by Jon Alvin and featured the bumpy head of Klingon with the Enterprise flying above. That was the poster available for purchase via the fanclub.
I have a lovely poetry about making the Trek films by Dr. McCoy - signed and hilarious. All about his castmates - no punches held. If interested let me know.
"Each signed item is unconditionally guaranteed genuine without time limit. Should an item be declared to be "not authentic", original purchaser must supply the written opinion of, at least, one competent authority. The examination of the item in question must be done in person. Evaluations over the internet, scans or photos are not acceptable.
We will refund the purchase price after documentation has been submitted. The purchaser's only remedy under this guarantee is the cancellation of the sale and the refund of the purchase price.
IMPORTANT NOTICE: Evaluation cannot be a standard rejection form letter used by dealers you intent for buy from."
Otherwise - you have 14 days.