Oprah may have gone crazy for this “Prestige Collection” of classic movies from United Artists on her TV show recently, but serious DVD collectors — or gift-givers serious enough not to balk at that nearly $900 price tag — might want to think twice. The fact is, practically all of these 90 films have been on DVD for a long time, and many are probably sitting in your collection already. (They’re a mixed bag artistically, but that’s another story.) What you’re really getting here is classy packaging for a company’s back catalog, which is also true for another high-dollar DVD box, “Essential Art House: 50 Years of Janus Films” ($850 retail, $650 when ordered direct from the label). Here, the theme isn’t a single studio but a famed movie distributor, the company that spent the ’60s and ’70s importing artsy foreign films (like the French New Wave landmarks of Godard and Truffaut) to America for the then-burgeoning highbrow market. In the case of “Essential Art House,” the films’ quality is uniformly top-tier, but all 50 titles have been out in attractive Criterion Collection editions for some time. Shoppers who want to spend a bundle on movies their loved ones definitely don’t already own should look instead to the impressive Ford At Fox, which at roughly $300 is around a third the list price of the other two but offers 18 John Ford films that have never been on American DVD before (and quite a few others that have). Alternatively, they could focus their big-ticket DVD spending on a complete TV-series collection. Or they could forsake the monster-set format entirely, focusing instead on smaller but all-new offerings, like the latest Looney Tunes Golden Collection ($64.92) for cartoon fans, the glamorous and witty Myrna Loy and William Powell Collection ($49.98) for devotees of vintage Hollywood comedy, or the marathon production Berlin Alexanderplatz ($124.95) for foreign film lovers who already own many of the titles in that Janus Collection.