Also factor in currently running mfg rebates by checking their sites (Michelin, Bridgestone, Goodyear, Firestone, Continental, Cooper, etc.). Always makes sense to get the $50-$70 rebate. Some big box stores already factor in the rebate to their pricing. You can then take that price to a competitor who will beat it by 5%, and still submit for the mfg rebate for a 2X coupon. Worked for me.
When ordering on-line you may have to pay for shipping at $50-$60 total. It's easier to find a local installer who will match that best on line price, and already stock the tires or not charge to have them shipped in from their warehouse.