I was pricing tires just a few weeks ago. Tirerack.com had some really good prices. Their system was that you purchase the tires and ship them to where you would like. They had a list of tire shops on their network. They all had ratings too, with prices.
For example, I was pricing the Revos. A set for around $650 shipped to a place nearby. The place had great reviews. So what I would have to do is have them shipped to a tire shop, (mentioned on the site) when they recieved them, they would give you a call to set up a time to install. Their price was $20 a tire to install. I thought it was a great deal, but Firestone ended up beating it by a few bucks.
Hope it helps.