Recently visited this shop to have a battery replaced in my watch. (Old Tag Heuer)  In the past this was  $10-$20. I was very surprised that they quoted me $79. They mentioned that this would include new seals, but would not guarantee the watch would still be waterproof.  They also mentioned that for $49 they would simply replace the battery. I wanted to get the watch running again, and did not want to chase around town, so I had them install a battery. However I believe this is too expensive & will need to find a new watch shop.