Flat panel TVs. My first lcd TV cost me 1700 dollars and was 36", 720p. 3 years later I bought one for 1200 that was 55 inches, 1080p. In the last year I bought a new OLED for 1500 bucks, 65" 4k, and it's picture quality is easily the best of any I've ever had.

Not only did prices go down during that time, but quality went WAY up.