A voice on the other end of the line claims to have located thousands of dollars you are entitled to. A pipe dream? Absolutely not, says Sidney Golub, who received such a call three years ago. He was so intrigued that with a personal investment of approximately $200,000, he launched the Coastland Group, in Stoughton, Mass., a company devoted to the recovery of unclaimed funds. With its proprietary database assembled over the past two and a half years by a nationwide network of field investigators, research personnel, and locally based lawyers, the company legally uncovers tens of millions of dollars a month in unclaimed funds for Fortune 500 companies, government agencies, small businesses, and private individuals. With Coastland's finder's fees ranging from 10% (for government agencies) to 50% (the business standard) of the claim, Golub expects 1992's gross cash value of retrieval contracts signed to be $16 million.