You can buy just the jet and JetRUs.com is great I just got mine from them and shipping was fast. As for the needles you can either search for clip style with the taper you need or just buy a kit.
http://www.dynojet.com/jetkits/motorcycle/kawasaki.aspx or
http://www.factorypro.com/ are both good needle kits but FactoryPro is your better bet.
Or you can just shim you factory needles and buy the mains and pilot jets you might need.