Hot Tub Time Machine cost $36 million. LINK: http://www.freebase.com/view/guid/92...0000000c4a954d
Stargate: Continuum cost $7 million. LINK: http://www.gateworld.net/movies/03.shtml
Stargate: The Ark of Truth cost $7 million. LINK: http://www.gateworld.net/movies/02.shtml
Both of the proposed movies, Stargate: Revolution and Stargate (Atlantis): Extinction have been already scripted, and many of the sets are currently standing.
Personally, I didn't care for either SG-1 movie. The franchise has become stale, and I have great doubts that either of the proposed movies will change that. But they also proved the franchises profitability. Which goes back to my original statement, which remains, why is MGM hedging their bets on an unproven, mid-budget comedy?