My vacuum cleaner is twelve years old and going strong. Before I bought this one I got a new one every three years or so. This one cost double what the others cost, but in the long run it's cheaper. The others always cost around $300, which comes to about $100 per year. This one has so far cost me half, $50 per year, and becomes cheaper every year of its life. My dad used to say, "We can't afford to buy cheap." He is right.
Built-in obsolescence may be good for the manufacturer and the economy, but not for your wallet or the environment. Long-term thinking is more sustainable - more money in your pocket, less stuff in the landfill.