All the Apple Stores I went into actually had special demo models of ipads with 'not for sale, demo only' or some such verbiage inscribed on the back. I presume Apple are make an effort to make it less rewarding for people to steal the things.
Regardless, there's no cross-over at all between for-sale stock and demo models. Your store's issued 6 or 8 demo ipads can't be sold.
On the subect of the Apple tablet, the laptop-with-a-touch-screen has been on sale (And failing to sell meaningful amounts) for well over 15 years. It's cheering that Apple has finally figured a middle ground of price and utility that will drive sensible tablet like devices in the future. If you don't like Apple, buy one of the other things that will appear in the niche Apple just created in the next 2 quarters.