Remember car salesmen are scum (even if they aren't, don't seem like it, just assume they are it can be hard with thier charm)...
Don't opt for extra crap like 'paint protection' its just a super expensive wax, no matter how much pressure, or how bad they make you feel about not buying xxx extra because of yyy, don't fall for it, stick to your guns.
As for price, as above, just shop around, don't be afraid to be a bit of a hard arse, don't let them guilt you into anything... if they want to make the sale, make them work for it.