TBH, you probably dodged a bullet. I'm not saying that Macs break down all the time, but when they do it's pretty expensive outside of the warranty.
I've had a few friends that didn't invest in Apple Care and each one has eventually needed something replaced just due to wear and tear. Most things are not that expensive, but one guy needed a new main board ($500 plus repair work) and another needed a new 15" screen ($600 plus repair work).
Don't get me wrong, I absolutely love Macs (using a Macbook Pro 17" non-unibody right now

) but I would never buy one used unless it was guaranteed by Apple and qualified for an extended warranty. The way that I look at Macs is like a BMW. You buy it knowing the costs involved, and milk the free warranty repair service for all it's worth. Should you need major repairs enough, it bumps into lemon laws (at least here in California) and you get a new one with which to purchase the extended warranty, and the cycle continues. Otherwise, you have a very sturdy laptop that never breaks down on you and needs only slight maintenance to upkeep for a long long time. Win-win if you ask me.
