NASA Mars Climate Orbiter: $193 Million
Nasa’s Mars Orbiter was the second probe in their Mars Surveyor Program, which also included the Mars Global Surveyor that launched in November 1996 and the Mars Polar Lander that launched in January 1999.
They were designed to arrive at roughly the same time to conduct experiments on the surface, climate, and atmosphere of Mars. It was supposed to arrive in orbit on September 23, 1999.