Is this really the time to be getting into the movie business? The world's largest publisher thinks so. Random House is teaming with Focus Features to form Random House Films, under which the two will cofinance and co-produce movies based on both new and old Random titles that is, if the movie rights are available and for a reasonable price. In line with Focus' history of small-budget, literary films (such as recent adaptations of John Le Carré's Constant Gardener, and Annie Proulx's ''Brokeback Mountain''), Random House Films has modest goals: about two movies per year at a maximum budget of $20 million, which leaves the publisher's more commercial, film-friendly best-sellers (like Dan Brown's Da Vinci Code) to deep-pocketed competitors. ''We're not going to buy the [film] rights that are selling for millions of dollars,'' says RHF president Peter Gethers. ''They can go right to Scott Rudin for that.''