I bought a refurbished Blendtec blender a while back. The jar failed after a year and a half; some plastic involved in the blade shaft bearing melted from the blender's own rotation. It's not designed to be replaceable and so I consider it a design flaw. It turns out someone already created a better jar with a significantly more robust, replaceable bearing assembly. It's called the Alterna-jar or something.

In total I'm in for about $450 and have a powerful blender that should last for at least the next decade.