In reply to djwilse:
We now have 6 kettles in use at home and in our apartments, and I'd say we probably have around 30 kettle-years of experience since we started here about 8 years ago, so all fairly recent. We don't buy the cheapest, as they're often under-powered, but neither do we buy anything because of its brand name or reputation. Typically, we might pay €25-30 for a kettle.
In that time I don't remember having to replace more than 3 kettles that packed in, thereby giving an average lifespan of around 10 years per bog-standard kettle. I don't think that's too bad really.