Tools
Being able to purchase cheap tools is perfect when you find yourself in an emergency. Yet, it would still be worth investing more on these items. We would rather have pieces of equipment that would last you at least a couple of years.
Batteries
Since they are usually poorly made, the batteries you would find in dollar stores could wear out quickly. Modern formulations were not used by many of them. It would also be likely for them to leak. It would be safer to go with brand names instead of the dollar stores when talking about batteries.