I pays to shop. When I needed new tires for my 03 Z06 the first thing I did was shop Tire Rack. After doing my research and settled on the new Firestone Wide Ovals I printed out the page showing the total cost (with shipping). I then went to two local FS stores. The first one said they'd match TR's price PLUS Illinois 7% sales tax would make that deal cost about $20 more.
The second store said they match the price to include sales tax. He had the tires in stock and within two hours I had four brand new tires mounted and balanced for the same cost as TR's (Sales Tax Included) and I didn't have to wait on shipping. All I paid for was mounting and balancing and tire disposal, which I would have had to pay for no matter where I bought the tires.
So shop around and use Tire Rack as a starting point. Plus it keeps the money local and helps keep folks working, at least in your home town.