INDIANAPOLIS, Ind. (WOWO): The “dairy cliff” could cause milk prices to skyrocket to $6 a gallon. The so-called dairy cliff became a topic of conversation last year as the 2008 farm bill and its milk subsidies were about to expire. The law would have reverted to one in place in 1949 that requires the federal government to buy up dairy products until milk prices hit a certain point. An extension of the current law has delayed that effect, but it expires on September 30, which means the price of milk could hit that six-dollar high by January.