The site map is a listing of all your internal hyperlinks. It`s usually used by a visitor of your site who is looking for information that may be "buried" and hard to find just by looking at your home page. On your site everything is exposed. Your use-ability is pretty easy, so in my opinion I don`t think it`s completely necessary. I would probably rename your site map to be a product listing.
A site map might look like this (of course with hyperlinks):
So on and so forth.
We used to have a site map on old versions of our site but have since thrown it away. Yet we are just getting ready to revamp our site and it may be a good thing to add. We need to make our site more user-friendly. You might want to take a look at our site to see on that needs a site map. We have a ton of info that can be hard to navigate through.
Another thought, I would probably move your header navigation bar down so it`s easier to access, perhaps underneath your logo.
One issue that might concern me is that your products are so varied, I would want to help feature products on your home page so that people can get a "feel" for what`s inside without browsing the pages. I might put a feature box that flashes pictures of your products on the homepage (or maybe in your left navigation bar or your header). Stuff is such a general term that people may not know what to expect when they go through your site. Though, I would probably try to capitalize on this generalization because of your theme, you don`t have any limits on what you can sell. I`d probably create a slogan, something like "Where you can find anything and everything for a great price and great service!" That`s a little lengthy, but you get the idea. And I`d put that underneath your logo.
Hope this helps and I wish you the best success!
Heaven & Earth Chinese Medicine Healing Center
"Your Health is Our Passion"