I got my oil at Advance Auto Parts. They have a deal for 5 quarts of Castrol Syntec + a Bosch Distance Plus filter for $26.95. So I got 5 (already had one) quarts of 5w-30 for the Firehawk.
They sent out a flyer that has a coupon for any non-sale items for $5 off if you spend $25, $10 off if you spend $50, and $20 off if you spend $100. So I got 9 quarts of 10w-40 for the Boxster, and that got me the $10 off.
So it worked out to about $5.50 per quart, and the filter for about $1.50.
The sale is this week only I think.