Same here,,,,I got a Gshock for Christmas and I have a Seiko that needs a battery. But the Seiko has a gas filled case and it needs to go back to the factory. last time it cost me 100 dollars.
15 years ago I got a Citizen Eco Drive Solar powered watch. I have bathed and swam with it, and it still works and keeps time and I have never, NEVER, replaced the battery or taken it to the shop.
$100 to change a battery is pretty steep. I would have it changed at a jewelry store and not worry about the gas (which is probably just dry nitrogen).