Chrysler Repair: thermostat 2000 concorde, coolant system, pain in the butt

Question
QUESTION: When I had my coolant system serviced I asked about getting a new thermostat installed and was told that was a very expensive job around 400$
Why is that? and are the thermostats life expectantcy longer than normal conventional ones?
Other than failure should it ever need to be replaced?

ANSWER: its a pain in the butt to get that thats why its so much.

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QUESTION: HOW LONG do they last??????????

Answer
cant tell U something like that.  This would be asking a DR at birth how long am I gonna live. Way to many factors are put into place once an owner of several owners get into it.
I have a 98 with a 2.7 and I have 181k miles on it never replaced it.
Seen them crap out at 23k.