2009 Galant Radiator

I recently purchased a used 2009 Galant and the “Service Soon” light was on the dashboard. I went to a mechanic and he said that my radiator sensor that was attached to the radiator was bad. He suggested I buy a completely brand new radiator with the sensor on it. He checked a couple of sites and said he didn’t really find anything except a radiator on the Mitsubishi site which was $1,500 which is pretty expensive. Is there any other sites anyone knows of that has my exact radiator for my exact year? Thanks