DCC is probably the best way for you to go when starting out. I would recommend either the Digitrax Zephyr or A MRC Prodigy Advance to start off with, which will give you expandability options as your layout grows.
I have heard they are pretty good, but have no experience with them myself. I usually get most of my stuff from toytrainheaven.com, trainworld.com, or modeltrainstuff.com
Everyone covered most of the places I shop... here's a couple more.
Best Selection of buildings
http://valleymodeltrains.com/
Also check Toy Train Heaven for low prices.
http://www.toytrainheaven.com