It's not a matter of what a dealer is willing to "entertain".
1. An 04 is now a 1 1/2 year old used car is the way a smart buyer would look at it, with its only advantage being it has zero miles on it. Once that zero miles becomes even 500 miles, (i.e. after you have driven it a week or 2), it's just a 1 1/2 year old used car with lower than average miles.
2. An 04 is 90hp down on the 05, and that 90hp makes ALL the difference in performance. To replicate that horsepower aftermarket will take a supercharger at $6200 to $8500 (depending on how good a deal you get on THAT). So, beyond the 1 1/2 years old used car mentality, you also have to subtract another $6200 to $8500 to get closer to a meaningful comparison.
Taking both points into account, under $30k is apparently what the market will pay, regradless of the dealers' desires.
That is not bad at all. I only bought my 04 SSR barnd new 2 1/2 months ago precisely because I COULD (and did) get such a deal. I was definitely not in the market for another $45k vehicle. Been there and done that, and the cost per mile at $45k is just more than it's worth to me. One of my recent cars was a Z06, so I speak with qualified experience.
Jim G