what you might have known: the Lockheed SR-71 "Blackbird" was the fastest aircraft ever produced, capable of reaching speeds over mach 3 (that's around 3500 km/h or 1020.87 m/s). it was made mostly from titanium alloys and has been discontinued for some years now. it had a loaded weight of 77 tons or 77 000 kg. it's main evasive maneuver in case of missle detection was to "go faster".
what you did not know: according to einstein's theory of relativity, the mass of a particle travelling at 1000 m/s increases by 1.000002 which means... if we consider a Blackbird, fully loaded at 77 tons and travelling close to mach 3, it's mass at that velocity will be precisely 154 grams greater, that is 77000.154 kg.
if we further consider the fun but impossible fact that the whole aircraft would be made of gold, at the current rates, the value of the plane at that velocity would increase by approximately 7000 US Dollars - close to the price of a new romanian car. however, using the same assumption, the initial value of that particular plane would have been 3.48 billion dollars, that's 3 480 million dollars. my guess is, since only 32 blackbirds were ever produced, the production costs were pretty much in the 3.5 billion ballpark.