What would be a fair price on a nice used Z4000??
Depends on whether I'm selling it or buying it.
Seriously, it depends on a lot of factors the main ones being condition and what kind of guarantee, if any, the seller offers. The starting point for me would be the current price for a new Z4000 - I believe MSRP is about $470 and some dealers are selling them for around $400. So I would definitely be looking at a price below $400. They appear infrequently for sale in the train club publications I get but one I saw for sale last year, described as "Like New," was priced at $300.