depends which year you are looking at, but here are some prices on ebay. 300zx

 

http://www.kbb.com/kb/ki.dll/kw.kc.u...ZX&12;NI;B3&&&

Here's a starting point. Because price depends on so many factors, I guesstamated. Like that, I made it up.
Year, condition, options, the area in which you live are all factors. You can also try www.kbb.com & just follow their basic formula to find out suggested private party prices. There's also trade in value which will be lower than what a private party would sell the vehicle for, so don't confuse the two.

 

IT also depends on the area you live in. Depending on the demand for Zs in your area, sometimes people seel them for less. Look around. try looking here:
www.autotrader.com
www.ebaymotors.com