Well, you can get kits for the 3.5 for a lot less than what I paid. I'm just picky and I refuse to put anything but OEM in my VX. The prices for each part are listed on my website.
Doing the belt only would be stupid, IMO. You need to do the belt and water pump at least. Once your in there, you have to remove the old belt, and when you do that, it take only a few extra minutes to swap out the water pump.
Bart