What is the probability of those things failing during the time you have the MacBook? I've had Apple portables since they were called PowerBooks and the only problem I've had that wasn't caused by violence was a battery swelling, and that cost me something like $120 to replace, not a big deal. If you add 5% to the price, that's probably about your expected cost for repairs or premature replacements if you don't have a habit of damaging your equipment.

If'd rather not take a low risk of a big repair/replacement bill and you don't mind helping Big Fruit make a bit more of a profit, you can pay them $50-150/year (depending on model) to take that risk. Multiply that by the number of years you expect to own the device to come up with a "real" cost including repairs/replacements.