An older SL model will be expensive to maintain especially if you are paying for labor. A W123 model (240D, 300D, 300CD, 300TD-wagon, 230-280E, etc.) will be a lot less expensive to maintain especially if you have a basic tool set and can rely on this and other forums for guidance. I currently own a well maintained 1985 300D and spend less than $500 per year for maintenance (I do my own labor). Parts are readily available and not outrageously expensive. I drive this car less than 5,000 miles per year.