I was surprised to see these Energizer CR2032 button cell batteries on sale at Amazon. If you clip Subscribe and Save and use the coupon, you can get it for less than $1 a battery.
https://amzn.to/34q7pE8
I was even more surprised to see that they're made in Indonesia. Although you need to check VERY carefully on all battery purchases on Amazon (even those that are "sold by Amazon") as counterfeit products from China are probably more common than legitimate products now.
CR2032 batteries are the most common size I use for my car key fob, my garage door opener, my flashlights, and a number of other gadgets.