Is Stradivarius still the most expensive instrument out there?

I read an article that said a Russian Czar paid well in excess to the $3.54 million dollar price tag that was set on "The Hammer" at Christe's auction house for a Guarneri that may very well be be made by Maggini. Is this evidence that lot's of things are changing in the world of music's most expensive avenue or is it just a one time thing. Will conessieurs be willing to pay a higher dollar amount for Guarneri and Maggini instruments above and beyond the well refined and acknowledged name that is now Stradivarius. I don't know, I think it may happen personally, but how warm of a sound is the world really after?