My advice, being a newbie nine-month machine owner--be patient, there are LOTS of machines out there and like all collectibles, condition is EVERYTHING. I jumped into my second machine--a '65 Williams EM San Francisco--that was a cheap CL find and in hindsight I'm regretting it a bit. I'll likely have as much in the restoration as it's worth and that's not including any of my time . . . I've gathered that's what we do here.
I've been using The Pinball Resource (www.pbresource.com) for my parts and they've been very helpful and patient. You will likely find that there's not a single source who offers everything you may need.