I think I need a lesson in Bike Maintenance

I bought a new bike last year - It's a Trek Pilot 2.1. It's a road bike, but not a racing bike though I've made it one. I want to have it for a while and figured the benefits (the set up is supposed to help people with lower back issues) would be better whether or not I continue with triathlon. I got some aerobars for Christmas and even if they don't really make me faster, I feel faster and that's what counts.

So here's the deal. I know I needed a tune up; my chain had dropped on me a number of times and was rubbing on the derailer. I know I needed new brake pads. A tune up at the shop was 69 or 99 dollars. It's a new bike with maybe 700 miles or so and I figured 69 was fine for what I needed. So the guy takes my bike and puts it on the stand. He immediately pull a single tool from his pocket and returns a few seconds later and declares that the chain is stretched and I'll need a new one... I got a case of the ICK factor, that kind of feeling that someone's taking you for a ride... I bought the chain and I feel awful... My 69 dollars ended up being $130.00. I hate not knowing. I hate that I had to rely on someone that I did not trust. I think I need a bike maintenance class or a Chiltons for road bikes or something that I can consult when that ick feeling starts creeping in...