MGM yesterday became the latest studio to throw its hat into the spec script ring, shelling out a hefty amount for “Getting Even With Dad,” a family comedy written by Jim Jennewein and Thomas S. Parker, sources confirmed yesterday.Although MGM execs would not divulge the financial terms of the deal–hammered out by Jennewein and Thomas’ agent, Risa Gertner of UTA–sources close to the negotiations say the purchase price was $ 500,000 against $ 1 million. According to sources, the script went out Monday night and was caught quickly in the middle of a bidding war between numerous studios, including Hollywood Pictures, Columbia, TriStar and Paramount. The deal closed yesterday. An MGM source said the script is “a highly commercial and entertaining script , well-structured, well-written and full of both hilariously funny and endearing moments.” The film will be produced by Katie Jacobs and Pierce Gardner, who are currently producing MGM’s “Triple Indemnity,” which Carl Reiner is directing. No casting or director has been set yet for “Getting Even.” While the film has not yet been budgeted, it is expected to roll in Chicago in late spring or early summer. The film is about what happens when a boy discovers that his father is involved in a crime. For Jennewein and Parker, the sale of “Getting Even With Dad” marks the second big spec script purchase of one of their properties. The former advertising copywriters sold their first script, “Stay Tuned,” for a reported $ 750,000 to Morgan Creek in 1990. The film, starring John Ritter and Pam Dawber, was released last year by Warner Bros. to dismal results. Jacobs, Gardner and Gertner were unavailable for comment.