(FORTUNE Magazine) – Zeke! Uncle Henry! Get those wallets into the storm cellar! A towering twister of hype, sent spinning by the 50th anniversary of MGM's The Wizard of Oz, is bearing down on consumers. When it hits in mid-August, an estimated $300 million will start to tip into the tills of merchants flogging Oz mementos, including wands, snow domes, plates, puppets, ornaments, and, of course, knockoff ruby slippers. That's $50 million more merchandise than Warner's Batman may sell by Christmas. Explains Eric Alberta, head of collectibles for Christie's East: ''Tons of people are hooked on Oz. When we had the ruby slippers here on display, all the young professionals wanted to touch them.'' Advertisers love Oz too. Says Doug Seay, an executive with Hal Riney & Partners, an ad agency: ''Safe programming is in short supply. You can watch Oz and know they're not going to talk about Satan worship.'' Procter & Gamble is joining an $8.5 million studio promotion of a 50th-anniversary Oz videocassette that plugs P& G's Downy softener. Anybody owning original artwork, props, or footwear from the movie might as well own gold. Sotheby's sold the Wicked Witch's hat for $33,000 in December. Philip Samuels, a St. Louis art dealer, paid $165,000 a year ago for mint- condition ruby slippers (one of six pairs extant) that had sold for $13,200 in 1981. Kansans take a dim view of all the Oz fuss. Many are miffed because MGM depicted Munchkinland in vibrant Technicolor, vs. Kansas in brown. ''We took a look at getting involved in the anniversary,'' says Hale Ritchie, CEO of Ritchie, a Wichita construction company, ''but it doesn't depict the Kansas we want depicted. It's not a giant positive.''