I just got a set of Fierce tires made by Goodyear.
I was cautious at first because they were very inexpensive but after some research I found that they were made for the tuner market but basically the same tread as the Eagle F1.
They are actual under the National brand which is owned by Goodyear.
http://www.fiercetires.com/
In fact the goodyear dealer had never heard of them before and was really surprised at how inexpensive they were. The way my boxster eats tires I was not keen on the idea of dropping 1200 bucks every 6 months.
Approximately 120 for the rear 265xx and 98 for the front 225xx 18 inch.
They look really impressive but they're on my new wheels so unfortunately I can't mount them until I get the proper wheel spacers. I'll keep you posted.