I purchased a 2000 VW GTI 1.8T in November 2003. The car had 15k miles on it (has 88k now). I took it to the dealer for scheduled 20k mile maintenance in Feb. 04. Although they did only what was called for in the owners manual (good for them), the price of the service prompted me to buy a Bentley VW service manual & all the tools I need for basic maintenance services, and to do all the work myself.
If I had kept going to the VW dealer for service up to this point, I'd have spent well over $1000, just for oil changes, air & cabin filter changes, rear brake pads, and new spark plugs. Doing all the work myself has cost me maybe $250 at the most, plus maybe another $100 for basic tools. There is definitely a lot of money to be saved if someone is willing to spend a little time learning how to do things for themselves. I know there are a lot of people who simply cannot do that, for many reasons, and I feel sorry for how much money they end up throwing away.
With that said, there are still jobs that seem routine to many of you, that I simply refuse to do, because of complexity and/or the PITA factor. Things such as changing ATF, flushing heater cores, replacing radiators, alternators.....things like that; I'll leave those to a couple of professional independent shops that I have come to trust over the years.
There is a timing belt/water pump replacement in my VW's near future. I still haven't decided whether or not I should attempt this myself. I have the Bentley service manual, and I can do the job for $250, whereas my local trusted VW mechanic will charge $750 for the same job. I just don't know if I should attemp this myself or not, since I have never done a timing belt before, and there is an expensive uh-oh factor if I don't do it right.