Microwaves are expected to last from 5 to 10 years for quality microwaves.
But I find that the cheap $50.00 Walmart Microwaves that I buy only last me around 3 years before I need to replace it with a new one.
The microwaves do not last as long as expected but even at 3 years of microwaving with the $50.00 cheap microwave I got more than my moneys worth with cooking in that microwave and have no problem spending another $50.00 to get a new microwave after 3 years.
I would love the microwave to last longer but with today's China made appliances they do not last as long and are made cheaply to break.