Most expensive card ever sold?

[fastnbulbous]

Today Francis Bacon's painting "Three Studies of Lucian Freud" became most expensive ever auctioned: $142million - £89.2million

http://www.mirror.co.uk/news/world-news/francis-bacon-three-studies-lucian-2786348

I suspect auctioned is the operative word as it seems a number of other paintings have sold for more, they just were not auctioned.

http://en.wikipedia.org/wiki/List_of_most_expensive_paintings

I was then curious of what people know (or speculate) what was the most expensive card sale that has been recorded?

Which basketball card do you think could fetch the greatest price?