Got the set for $665 shipped during a DTD sale a few months ago. Honestly wasn't expecting the RT660s to last this long. I am making changes to the car (sway bar etc) so having fresh tires is wise before fiddling with things. (I intend to test front sway bar stiff vs soft in May, and maybe some VCDS and tune related stuff as well).
Also just wanted to try something different. My last 4 or 5 sets of tires have all been RT660s.
Edit: also I've found that selling used but not trashed tires a bit early you can make back a bit more. Maybe not so much on this size, but on my Mazda2 when I autocrosses a lot I'd buy a set of RE71Rs at the beginning of the season for $450-500, sell them less than half worn in June-July for $200-250, and buy another set, and sell those again the following spring for $200-250.
I'm still only buying "one" set per year $$$ wise... But was on fresh tires not heat cycled out again halfway through the season.