I buy my InfoKey batteries on eBay and only get Sony branded ones. They last 2 or 3 years. They're less than $3 each (with free shipping) and less than $2 each if you buy two and even less than that if you buy 4 or 5
https://www.ebay.com/itm/5-pcs-SONY-...ss!39565!US!-1
There are other good brands out there (Maxell and Duracell) but the Sony ones work best for me
Don