I agree with that to a point. One of the biggest difficulties with a home repair is obtaining parts. I'm not a pro, and while I know parts are available online, if it's something you need now, you may not always have it available like the pros often do, especially nowadays with the more modern and often proprietary bits and pieces.
Of course, I still wouldn't spend money on an extended warranty- that's merely a cash grab, and an effective one at that. Forums like this one are indeed a very valuable resource for helping folks muddle their way through repairs. Provided you can access replacement parts, groups like this greatly help to solve problems often almost immediately, so if it's something unforseen, you can quickly snap some pics and post your questions. Find a manual that will do that!
I'd suggest the best bet is to visit a forum like this at least once a week and read the threads, thoughts and ideas posted by other people- this will help you make an informed decision when it's time to decide whether to repair or replace items, and what to look for in the next one. All the info is here, it's up to you to absorb and apply it!