How much do components really matter for a non-competitive rider?
Here's a little bit of information that's in contradiction to "higher end equals better"  Lower end components can sometimes last longer and be less problematic than the higher end components.  In order to shave off every single gram they sometimes have to skimp on materials.  Also, the tolerances are much tighter, and high end components can often be difficult to tune because fractions of a millimeter matter.  An 8 speed derailleur can be quite a bit out of tune before you'd notice. The same can't be said for a 10 speed.  With so many gears, there's very little room for error. 10 speed chains are thinner, and therefore stretch and break more. 

Don't go for very low end stuff, because it often will be made bad, and will break faster.  But different components are built with different goals in mind.  Very high end parts are often built for racers, who have professional mechanics who can ensure that everything is tuned properly, and parts are replaced more frequently.  If you buy decent components and maintain them well, you'll get plenty of life out of them, and you'll be able to replace them when it's necessary, instead of waiting until it's too late.