I do all of the maintenance (Jiffy Lube? - I think not!) and MOST of the repairs on our cars.
Whatever I don't know, I can find out fairly easily from knowledgable friends and coworkers.

The only time I don't do the work myself is when I need a specialized tool that costs more $$$ than I am saving by doing the work myself - then it gets farmed out to one of my friends (whom I know and trust).
$400.00 tool (I MIGHT use twice in my lifetime) - $200.00 saved by doing it myself = I'll save myself the bloody knuckles this time.