Your budget is a DE, dont look at anything else as it may may a dog. Also the DE has the cheaper tax. I would have thought you can fine a decent DE (up to 2005) for that price.
All the models are great, there isnt a bad 350z model. Id try Pistonheads. Scan around and take your time, its easy to get excited and go for the first one you see.
You can try here too, that way youll be able to see some sort of history from the owner if theyve posted up on here. Good luck!