I have my mother's Cartier tank with an alligator band from the 70's. It's a wind up and it keeps time perfectly. Yes, full service is in the $400-500 range but that is done every 5 years or so. All high end watchmakers recommend this servicing, not just Cartier. And full service is more than a battery change, they take apart the entire watch and clean and lubricate all of the moving parts, as well as make any adjustments and polish. I love Cartier watches. I have a Santos Galbee automatic that makes me so happy, too. I say go for it, the tank is timeless!