Tools
It is fine to use cheap tools if you are in a rut. However, these are things that are worth shelling out money for. Ideally, you should get something that will serve you for a few years at the very least.
Batteries
The batteries available at the dollar stores run out of juice quickly since they are of lower quality. Most do not use new formulations. On top of that, there is a chance that they will leak! When we talk about batteries, you are better off using brand names and not cheap ones.