Plus, the CTTS needs 19" wheels or larger. If you run snows, it's nice to have the 18" option.

That said, why not just get an 04 CTT? Same interior as the 957, established as reliable, and you can pick one up in the mid teens with 100K miles or more with full records. If you're going to wait, then I'd wait for the 958 Turbo to come down in price. No point in spending the coin on the 957 when the interior, chassis (aside from PDCC), and running gear is the same as the 955. The 330 is a nice car, but it's not nearly as capable as the CTT.

 

I paid 23k for my 06 CTTS a year ago with 105k miles (tubes were done)
25k seems a little high to me for it but for a couple thousand if you like it its worth it