For a quick and easy price quote on tires, check td4l.com and
http://www.tires-easy.com. Be aware that there are advantages to buying from a local tire shop, even if it's slightly more expensive. If they ship you a tire that has a defect, or perhaps a leak that can not be detected until it is mounted on the wheel, then you have to deal with shipping hassles, and you are eating the mounting/balancing cost. If it's a tire shop, they just slap a new tire on on the spot. So there is some inherent risk with purchasing online. It happened to me once.