Household vacuum cleaners question?

We bought an Oreck when we moved into our downsized house. We put new carpet in every room except the kitchen and bath, so we needed something better than the junk I got off the curb and fixed.
The Oreck was expensive, but I watched for a sale and paid $300 for a $500 vacuum. It's worked flawlessly. Nice and light, but well made. I change the bag when it starts to get full or starts to stink. 2-3 times a year. The bags are pretty cheap.