<p>For sports the D3 is much better than the D800 or D600, simply because of the 9 frames per second capability. It's a great camera and has a much nicer viewfinder than the D800. Of course it's much bigger and heavier.</p>
<p>As to whether it's worth buying the particular one that you refer to, that depends on a number of things. How much has it been used? (How many actuations) What currency is the 2,500?</p>
<p>Personally I would tend not to buy something so expensive second hand. I'd like to have the security of a valid warranty.</p>
<p>A final thought: the D3 is fairly old technology now, not that it is not perfectly adequate for almost every possible photographic application, but again, personally, I would prefer to go for something a little newer.</p>