Aren't there laws about businesses fairly arbitrarily offering products/services to some people but not others?The way I see it is OCUK is going to sell out of these cards in any scenario.
So why not look after their active forum members first that contribute.
It's not such a terrible idea.
Just create a VIP members group and VIP area, and have a strict criteria to flow to be a member of that group.
Minimum post count and member join date requirement, no one who has broke the rules etc.