Well, I don't think they list them (CZ that is) in their on line catalog anymore. If so they aren't being made and will probably just decrease in availability and increase in price over the years.
I don't think you could buy a new one for $500 (I've never even seen one for sale at all the gun shows I go to every year).
I really like the 85's (for some reason) and if I found one that I thought was worth $500 I'd probably buy it (even though I don't need it).
If you think the condition and price is good and you want it, go for it.
This reminds me, I've been wanting to order an extra slide release for mine, as a spare, just in case that part becomes scarce some day.
Good luck with it. If you do get it, come back to this thread with some pictures.