I bought a countertop popcorn popper. You can get one for about $20. Buy a bag of popcorn in grocery store for maybe $2.
You can pop bags of popcorn for far less money and control your toppings.
When you purchase already popped popcorn most likely it has preservatives...you con't want that.
Also check the reviews...they are not that good.
This is just my opion...pop your own..taste is far better...cheaper...and you can control your toppings and no preservatives.