Always use a new bag - there are three dogs in the house so the bags fill up quickly with dog hair and gorilla dust. This is the cheapest price I can find and as long as you don't overdo it your vacuum will work great. I've just replaced a 26 year old Electrolux with an identical newer model (ProCare 15 Multi-Surface/Canister Vacuum) and I'm pretty sure it's lasted this long as I've changed the bag a lot.