I built a kid's treehouse and needed roofing materials. The people at Al's walked me through choosing something that would work and explained how to do it. I was expecting them not to be interested in taking the time to help someone that had such a small order but I was pleasantly surprised how helpful they were. I had shopped around and their prices seemed low relative to some other inquiries I made.
Pros: Helpful advice for do-it-yourselfer