Cost. "$125 million Mars orbiter" — CNN, 30 Sep 1999 (contemporary report): https://www.cnn.com/TECH/space/9909/30/mars.metric.02/ Consistent with NASA/JPL arrival press kit (1999): "$193.1M spacecraft development, $42.8M mission operations; total $235.9 million for both Mars Climate Orbiter and the Mars Polar Lander (not including launch vehicles)". https://www.jpl.nasa.gov/news/press_kits/mcoarrivehq.pdf NOT used: "$327.6 million" (Wikipedia / Guinness) — does not match the NASA press kit breakdown.
Timeline. Launched 11 Dec 1998; arrived and lost 23 Sep 1999 during Mars orbit insertion (~9.5 months). https://en.wikipedia.org/wiki/Mars_Climate_Orbiter ; press kit above ("Arrival: September 23, 1999")
Cause. Built by Lockheed Martin (Denver); navigated by NASA JPL (Pasadena). Ground software delivered thruster impulse data (AMD file, angular momentum desaturation events) in pound-force seconds instead of the specified newton-seconds, so the small velocity changes were modelled low "by a factor of 4.45 (1 pound force = 4.45 Newtons)". Mishap Investigation Board Phase I Report, 10 Nov 1999: https://discovery.larc.nasa.gov/PDF_FILES/MCO_report_2.pdf CNN 30 Sep 1999: https://www.cnn.com/TECH/space/9909/30/mars.metric/
Altitude. Final trajectory correction (TCM-4, 8 Sep 1999) targeted a first periapsis of 226 km; the actual approach was about 57 km; ~80 km was regarded as the minimum survivable altitude. Phase I report above; https://en.wikipedia.org/wiki/Mars_Climate_Orbiter