I just traded in my 2004 EX for a 2011 EX. Lots of problems with the '04 - felt the tranny starting to slip but no error codes yet. I had 79k miles on the car with some dings in body and they initially offered $4500 which I laughed at and walked away. The caught me and offered 6k but I still declined b/c KBB, Edmunds etc had it at least 7k.
A friend suggested carmax b/c they pay well for used cars so I went over there and in 30 min they gave me in offer in writing for 7k for my 2004 that was good for 7 days. I called the dealer and told him I have an offer in writing from carmax for 7k and if he could match we had a deal. We already had a set price for the 2011 from USAA. He finally gave me 7k for the trade-in. So, if you have a carmax near by, go there first and get an appraisal and then have the paper in hand at the dealership.