2006 Impala Mirror Inside Gasket

I was washing my 2006 Impala and hosing out the soap on the passenger side mirror and out comes this little gasket in pieces from inside the mirror. I called the auto supply houses and they don't have the gasket. Called the local Chevrolet dealer and there are 3 options. (1) buy new mirror (2) buy new motor with gasket (3) buy entire mirror assemble. $185.00 for assemble. He never gave me a price for motor and gasket. Anyone have any suggestions and what purpose does the gasket serve. I'm assuming it protects the motor connections.