Three investors have until April 15th to work out a deal to buy Bon-Ton Stores, Incorporated, and its assets.  Bon-Ton filed for bankruptcy in February and notified the state of Wisconsin it is closing 12 stores and its corporate headquarters in Milwaukee last week.  Washington Prime Group, Namdar Realty and D-W Partners have submitted a letter of intent to buy Bon-Ton.  Theirs was the only offer which would keep the stores open and the 22-hundred employees on the job.