Hi Ellen,
RFF is a gear oriented site and members pride themselves for making great deals on trading stuff on ebay, etc. On the other hand, a search will provide you with reports of such trades going wrong, and of the hassle necessary (camera repairs, etc) when this happens.
US 2100 is a "normal", maybe slightly higher price for this combo when compared to our classifieds, ebay, etc. But the fact that you can hold and inspect the camera, and possibly return it when something is wrong is at least worth several hundred dollars in my book.
It's a great combo. The 35/2 v3 is my favorite 35 Summicron. I would go for it. Before, do some simple checks in the store, make sure the lens is clean against a flash light, the meter works, the RF is aligned, and the shutter curtains close completely and have no pin-holes. Check the speeds by listening to them. Watch for corrosion, bubbles in the paint, and in the flash connectors and battery compartment.
The correct hood for the v3 is the Leica 12504. But you can buy cheaper screw-in hoods from ebay, and generic 39mm caps as well.
Good luck !
Roland.