Hmm. In Germany, I shop batteries at conrad.de - an electronic retailer chain. They're expensive, yes, but the stock is quality, you can get weird stuff like coin cells with solderable pads on them (which gets handy when you're repairing old stuff with soldered batteries!) and you can have them ship to the nearest store for pickup.
https://www.amazon.com/dp/B00HZV9TGS/