The most wanted domains Google has never been used (short-lived projects)
Zero.com ($330k / 2008)
Like.com (The former comparison shopping engine co. joined Google)
Disco.com ($250k)
Sonar.com (former DoubleClick)
Etc...
Today’s value?
Disco and Like - at least $2 mil each.
Zero and Sonar - at least $1 mil each.
But 1, 2, 10 million, that's pocket change to Google. So I assume they have no intention of selling these.