totally depends on your price range, intended usage, and what you want from the d2.
I got mine from a dealership with 16k miles (358 days ago) with an extended warranty and at below kbb value. It was a steal. I got a good price, low miles, clean title, and a dealer backed warranty I can depend on. I still am modifying the car, but not at such a rate where my warranty is voided. its a daily driven street car which i take offroad whenever I can.
now if you want to make a trail rig outta your 2004, go with a private party, more than likely prices can be bargained lower, no warranty to void. mod away.
dealerships give you piece of mind, but ass a pain in the ass.
private parties give you a good price and usually have a wider selection