I was worried about being able to buy batteries in Central America, especially AAA batteries so here’s a report as of June 2012 in case you wonder the same.
Batteries in Honduras
In an upscale department store in Honduras, I easily found Maxell AAA that are dated January 2016 in a 2-pack for just 29, which is US$1.50.
In a same-mall electronics store batteries were 39L or $2.
I forgot to check the price of AA batteries.
Batteries in Guatemala
In Guatemala the AA were a bit over US$3 wherever I saw them.
Batteries in El Salvador
San Salvador, the capitol city, has plenty of upscale stores and I am sure you can trust the batteries you buy there. But when I needed batteries I was in a small, out of the way beach town. There, the batteries were a brand I hadn’t ever seen and the AA batteries didn’t last an hour in my tiny, power-efficient video camera. I have no idea how long they’d sat on the shelf at the local shop. (It wasn’t in any shopping area.)
A huge takeaway to remember is to buy your batteries in places with high turnover.