It was 1990. They had, I think, 6 or 9 different 'helmets' you could buy. Off th top of my head I remember:
Stormtrooper, Darth Vader, Chewbacca, Yoda, Imperial Guard, ?C-3PO?
Now, my parents told us we (myself and my sister) had $75 in spending money. The Stormtrooper was the least expensive helmet, right at $75. Since I wanted to be able to get things at other stops on the trip, I decided against buying anything.
Now that I think about it more, the Chewbacca might have been as much as $200.