We purchase a 2004 Prius new. In the second year the headlights started going out. We took it to the dealer who wanted $300 to change each headlight (a total of $600). Started changed the headlights myself at that point. On average I have had to replace the headlights at least 3 times a year at a cost of $15 to $50 per headlight, we have tried them all. Recently changed the driver's side headlight only to have it blow out with a month.

Auto repair shop recommended replacing the connection buds, which sounds reasonable since the car is 13 years old at this point. The car itself has been great over the years with very little maintenance. The biggest issue is the unreliable headlights. Definitely poor engineering design.