You have all of the proper price points vs mileage etc from what I normally see. You have to understand that for the guys that have the low mileage Z's that have spent the time and money to maintain them and mod them correctly aren't just gonna let them go under normal circumstances. Every once in a while someone needs to unload one of their toys but most of us have some sort of attachment to our cars. We really need it to be "worth it" to sell them. I would venture to guess that you'll be waiting a while for the deal you're looking for. Good luck with the search.
I've owned a 350 as well. I didn't have any major issues or complaints about mine. It was an 03 and the newer ones definitely had better interiors, headlights & a few other things that I can't remember off the top of my head.