The Amish suffer from genetic disorders due to inbreeding. From the Wikipedia article someone linked to:

Some of these disorders are quite rare, or unique, and are serious enough to increase the mortality rate among Amish children.

I criticized the practice of inbreeding in my first comment.

We're talking about costs, not mortality. You also can't equate mortality with healthy or unhealthy lifestyle. Many of the things in the lifestyle are healthy, the two biggest being more physical activity and less processed foods. You can "live" in a nursing home for a long time. But quality of life is an important factor not captured in your mortality figures, including things like some of the lowest obesity rates (and chronic illnesses that go with that).