Buying a New Car

[glatt]

We're probably going to buy a used car this weekend. Haven't chosen it yet, but once we do, how do we negotiate price?

We're looking on cars.com at mid-sized sedans that are recommended by Consumer Reports in the $6K to $8K range. These are going to be cars from around 2003, give or take, and have in the neighborhood of 100K miles on them.

Do I just randomly ask for $500 less than the price they are listing the car for? I'm not sure how I could find out what they acquired the car for, presumable when someone traded it in. It's not like I can get dealers competing against each other, because the supply is fairly limited. Whatever car I decide I want, there are going to be no other cars just like it on the market in my area. They will have different mileage or different options.

I assume the price tag on the used car will be negotiable. I'd like to negotiate from a position of at least a little knowledge. I won't have anywhere near as much knowledge as the salesman who knows what they paid for the car and what they will take.