There are few safe bets in Hollywood, but you can have no fear about putting your money on Paranormal Activity III to win the top spot at the box office this weekend. Forecasters disagree about how much the movie will make -- they're predicting anywhere from $30 million to $45 million -- but no other new film or holdover is expected to do even half that amount of business in the U.S. and Canada. It'll still be a winner, however, having cost just $5 million to produce, about $2 million more than Paranormal Activity II . The original Paranormal Activity was made for $15,000. The latest installment in the franchise does not face much in the way of serious competition. A 3D remake of the Alexander Dumas classic The Three Musketeers will likely produce only about $15 million in ticket sales (although it's expected to perform quite better overseas). The Rowan Atkinson spy spoof Johnny English Reborn will probably earn about half that much in the U.S. (it's already a huge hit overseas, where it will likely cross the $100-million mark this weekend). And playing in just under 1,000 theaters, the inspirational The Mighty Macs is expected to earn around $4 million.