We'll the dealer is probably into it for about 75k or so, depends on how long they have had it.
I'd negotiate up from there. Around 80k or so would be a great price!
Also make sure you understand the difference between CPO and Elite CPO warranties. If you are buying the car and plan on keeping it for a while it's something to consider.
Elite CPO = 1yr/25k additional warranty on top of the factory 4yr/50k, so 5yr/75k total.
Regular CPO = 2yr/50k additional warranty on top of the factory 4yr/50k, so 6yr/100k total.