The most you should pay, before TTL, is True Market Value.
Better if you can beat TMV.
Assuming you're buying from a dealer, and you're looking at the 4 door sedan with an automatic, in clean condition, that number in my zip code is $29,015. You should appraise it yourself at that TMV link to account for what options are included in "fully loaded".
So your offer should be closer to a Private Party price, but you probably won't get very far starting at the Trade-In number.