The number comes from estimates of the value of any recoverable water on
the asteroid worth as much as $65 billion as fuel in space plus the
value of nickel, iron and other metals worth as much as $130 billion as
construction materials.
http://blogs.marketwatch.com/thetell/2013/02/13/asteroid-set-to-buzz-earth-is-worth-195-billion-report/

A local ministry official said the meteor shower may have been connected
with an asteroid the size of an Olympic swimming pool that was due to pass
Earth at a distance of 27,520 km (17,100 miles) but this could not be
confirmed.
http://www.reuters.com/article/2013/02/15/us-russia-meteorite-idUSBRE91E05Z20130215