How much is a used D300 worth?

Not a D300s, but a plain D300. What about a Nikkor 18-70mm F3.5-4.5G lens?

Go onto ebay and check completed listings.

lens is worth next to nothing, everybody else got one with their camera too!

I have seen nikon 18-70 go for for less than 150$

The D300 alone for about 900$

I have seen the kit D300+18-70 + grip, go for 1000$.

It all depend of the condition and the person who sell it, if you know were to look you can find good deal.