Some things fall somewhere in between. Your grandfather's watch is a marvel of mechanical engineering that will keep time adequately for centuries if taken to a watch-shop for maintenance every few years. That maintenance will cost more than buying a new timex would, and the timex will keep far more accurate time. Timex's are disposable. When the timex's battery dies it will probably cheaper to replace it than to replace the battery. However, their function is superior for all practical purposes. Many people currently enjoy the aesthetics of mechanical watches. They're currently enjoying a major surge of collectibility, but that wasn't the case twenty years ago and it may well not be the case twenty years from now.
The real trick is to figure out what can last and what should be treated as disposable. e.g. Say you're building a home theater. Amps have changed very little over the last 20 years. Preamps and receivers go obsolete every few years. If you spend $5000 on a Bryston amp it will easily last 20 years (that's how long it'll be under warranty!), but a Bryston preamp will be hopelessly unusable long before that 20 year warranty runs out.
There are also big variations in short-term durability too that aren't necessarily correlated with price. e.g. Macbook air's and the new retina pro's are gorgeous pieces of engineering, but they're made to be disposable. If you spill coffee on them they're basically done. You can't remove the battery and take them apart to clean them (proprietary screws) like you can with a much cheaper laptop and Apple won't lift a finger to help you. This is a case where our perceptions of what is durable and high-quality can actually lead us to buy something that won't last as long!