You do realize that Amazon is increasingly becoming an order processing house for people running on-line businesses out of their garage, don't you? It doesn't take much to buy a crate of cell phone chargers from a Chinese vendor and then sell them one-by-one on Amazon. Yes, Amazon takes the order and handles the money, but the guy in the garage is the one who actually ships the order.
Not necessarily. They can also have Amazon ship if they set up that arrangement. They just supply Amazon with the stock. I know the base charge is 15%. not sure about Amazon fulfillment charge.
More than a few times I've also purchased things from eBay only have have them 'fulfilled' by Amazon. I try to check Amazon for a better price, but many times that doesn't happen.
I'm in the camp that if SM is taking SDS-200 preorders, and the page shows 'in stock', it means the preorder is 'in stock' and they are still accepting them. That may mean they have more units enroute than they have preorders to fill. Now someone show me a non-preorder page that shows them in stock.