The cost of living in Fairfield County is among the highest in the country, but the cost of dying has become pricey, too. To make matters worse, burial plots are running out. Most cemeteries, where single plots can cost $1,000 and more, are likely to be filled within 10 or 15 years, according to funeral home and cemetery managers. ``Cemeteries are going to become a thing of the past,'' said William E. Magner Jr., who manages Willowbrook Cemetery in Westport. Harriet Steuber, president of a group that administers Union Cemetery of Norwalk, said that once space runs out, ``I guess we'll all have to be cremated and dumped in the sound,'' referring to Long Island Sound, the stretch of ocean off the Connecticut coast. ``I don't like to think about it. It gives me the creeps,'' Steuber said. One solution may lie above ground. Mausoleums up to four stories high are becoming increasingly common in the region. Construction of one such facility by the Roman Catholic Diocese of Bridgeport began this month at Darien's St. John's Cemetery. ``It's one of the, shall we say, contemporary modes of burial to help meet the lack of space,'' said Monsignor Nicholas B. Grieco. The structures are often multistory units containing hallways lined with crypts. Each floor might contain up to 100 bodies. ``Think of it as a giant bookcase with slots,'' Magner said. But mausoleums are not cost-savers. They are generally more expensive than below-ground burial, Grieco said. Other cemetery managers say mausoleum interment is about twice the price of traditional burial. Sometimes it's possible to economize. At St. John's Cemetery in Norwalk, a two-grave plot can be used for four individuals _ one on top of another. The practice is allowed at the discretion of the cemetery, which charges $1,050 for the double plots. But the cost of the grave site is only the start. Add to that payments to the cemetery for digging the grave and the price of a concrete vault, plus a foundation for a gravestone and it could cost as much as $2,000. Cremation, which one local funeral director said now accounts for about 30 percent of his business, can save several hundred dollars at the funeral home and there would be no cemetery costs. Basic cremation and transporation services can cost as little as $160.