I like TireRack and have always found their information very valuable but whenever I ran the numbers (and this goes back quite a few years), I have always found a warehouse club cheaper, not to mention better service. So I decided to try once more using your Goodyear coupon link to TireRack. I don't want to sound like a Costco commercial so this time I used Sam's Club. Their rebate is an instant rebate as oposed to the mail in rebate at TireRack (no big deal here). I used a Goodyear Assurance ComfortTred tire which both places sell, sized for the RX. Sam's Club comes out $22 cheaper per tire.
You do make an excellent point about buying used tires off ebay. I am sure that is real cost effective, especially if you like to change tires before the end of their useful life or just want to update the rubber wothout going all the way to new.