I'm afraid the Linden Bear Collection ship has sailed. I personally collected 179 of them between 10/31/2008 and 03/02/2009, and looking at my list I'm afraid almost all of the Lindens who I got bears from are long gone. The Linden Village sims used to be almost full and most Lindens back then had set up a home, and many of them had a bear. Many bears were also issued for special events. Sadly yes the era of finding Lindens in world who would show up at events or you might see out shopping or at the Linden Village area is just a memory.