Tools
Cheap tools are fine when you find yourself in an emergency. However, it is always worth spending more on these things. You want pieces of equipment that can last you at least a few years, after all.
Batteries
The batteries you find in dollar stores will run out quickly because they are normally poorly made. Many of them do not use modern formulations. It is not improbable for them to leak as well. When talking about batteries, it is much better to go with brand names instead of these reasons.