One of the classes I took in university was on electrochemistry and fuel cells. It was very interesting, but was also a reality check on the hype of hydrogen fuel cells vs. the reality. One item in particular that stood out for me was that the catalyst required for efficient, low temperature hydrogen fuel cell operation was platinum. While platinum isn't the most expensive metal out there, gold having passed it in price not too long ago, it's way up there. As I recall, the raw platinum required to make a fuel cell cost a significant fraction of the cost of a normal car, and that was before they processed it into a useful catalyst. Since then, they've improved the structure here and there and reduced the amount of platinum required bit by bit, but it's still a lot.
Not long ago, however, some researchers in Finland figured out a way to reduce the amount of platinum by more than half.