I don’t usually buy the extended warranties on electronics that sales people love to push on you. These programs are mostly designed to take cash out of your pocket, up front, while delivering little in the way of actual service, down the line. Given that: most new purchases already come with a 1 year warranty, defective electronics will usually fail in the first month of use, otherwise devices containing few moving parts generally last for years; these companies are selling you a service they know you’ll probably never need. It’s extremely profitable for them, at your expense.
But there is the rare exception. If you’re buying a computer from Apple, I generally recommend purchasing the AppleCare Protection Plan for that device. I doubly recommend it if you buy a laptop computer, or frequently need to call tech support for help. Portable devices take more abuse than a computer that just sits still on a desk day after day. And AppleCare gives you 3 years of telephone support and repairs, if anything goes. When laptops do fail, all but the most minor problems are repaired by replacing the motherboard. The cost for a new motherboard is usually 2-3 times the price of AppleCare. So one repair in 3 years can twice-over pay for the upfront cost of AppleCare. Plus the AppleCare staff generally make the repair process about as quick and painless as it could be; their “support has long been the finest provided by a major computer maker”, according to Consumers Union.
I am often asked, “Must you buy the AppleCare at the same time you buy an Apple computer?” No. AppleCare can be purchased any time while the original 1 year warranty remains in effect. I recommend buying it within the first 90 days, to have the full benefit of the technical support you’re paying for. You don't have to buy it directly from Apple, so buy wherever you find the best price. But be sure it’s “AppleCare” (not some crap warranty offered by Best Buy, or whoever) and that it’s the right plan for your model of Mac.
You can read more about it and look for a good price here: