Canister vacuums vary widely by brand. So, different brands and models of canister vacuums will have different lifespans. More expensive models generally have more positive customer reviews and better warranties. However, if you are seeking a simple vacuum without special features such as a retractable cord or HEPA filtration system, there are several highly rated vacuums around the $100 range.
The terms of the warranty for your vacuum will give you a good idea of its lifespan. Some of the highest rated and most expensive vacuums come with a 10-year warranty. Other warranties are generally two to five years. Contact the maker of your vacuum directly to find out the terms and conditions for your particular warranty.
Proper care and maintenance will preserve the life of your canister vacuum. Remember that you should never pull a canister vacuum by the power cord or jerk on the hose. Both of these moves can cause serious damage. Be consistent about changing the vacuum cleaner bags when they are full to maximize suction power and to prevent damage to the motor.
Replacing the belt on your vacuum once a year can greatly increase suction power and extend the life of your vacuum. It is a small investment for upkeep when you consider the cost of the vacuum itself. Remember to follow your manufacturer's instructions for changing filters and brushes, as well.