There are arguments to be made either way -- buy a service contract, or fund it yourself.
Funding it yourself is great, unless you start putting away $137 each month, and a few months down the road are faced with a several thousand dollar repair bill for something major.
A service contract is basically an insurance policy. You know, just like you have for your house, your car, your health, your life, and so on. You roll the dice with all of them, and that's why you probably have insurance.
For example, I always buy CPO cars (certified pre-owned), and I do it for 2 reasons. First, the initial depreciation hit has already been taken, and second (especially in the case of Volvo and MB), the warranty from the manufacturer is better than the original warranty that came with the car.
So, it's just a matter of how much of a dice-roller you choose to be!
. . . never confuse education with intelligence, nor motion with progress