It's a good deal but you can still negotiate and make it better. Get the price down by removing the flash unit and the filter. You can buy better ones later.
For latest prices search on the internet and you'll be more aware.
My only doubt about the deal is the reason why the person is selling it. The D300 offers no great advantages to a person who has done just 500 shots on a D80. Secondly I fail to understand the reason for selling the second lens and the flash too.
