Stock sizes are 315/35/17 in the rear and 275/40/17 in front. I got my set of R888s shipped to my door for $760. This doesn't include mounting and balancing of course.
I got mine from TiresDirect.net. Here is the link for the fronts:
http://www.tiresdirect.net/TOYO-Prox...98W-P4744.aspx
They are not showing the rear size so maybe they have run out. They are supposed to be phased out in favor of the newer R888R, which has a different tread but similar pricing.
Due to the softer compound, one thing to consider regarding colder temperatures and long-term storage is the following consumer advisory from Toyo:
https://toyo-arhxo0vh6d1oh9i0c.stack..._-10172017.pdf