All good points but it seems to me if you pay half the price of the kit for 1 or 2 parts (including shipping) from the kit then you might as well just spring for the kit. This way you have extra stuff for later. Case in point, I've been looking for a set of wheels and tires from a certain kit. I saw two sets just two days ago on ebay sell for around 20 bucks with shipping for each set. If thats what they are going for then I'de just spend a little extra and buy a whole kit.
Just my .02