FIRST FEDERAL FORT MYERS <FFMY> TO MAKE PURCHASE First Federal Savings and Loan Association of Fort Myers said its board has executed a letter of intent to acquire First Presidential Savings and Loan Association of Sarasota, Fla., for 8,500,000 dlrs in cash. The company said a definitive agreement is expected to be executed by May 15 and the transaction is expected to be completed by year-end. The purchase price is subject to an increase on a dollar for dollar basis to the extent that the net worth of First Presidentail exceeds 4,100,000 dlrs at the time of closing, the company said.