I just finished doign a bit of web research on this type of item
Now, I don't have all the exact specs on hand, but I did find a whole bunch of existing touch-screen notebooks where the screen turns around and can be set down over the keyboard like a tablet and even a tablet with a keyboard unit it can connect to - the Acer Iconia W series - all about or under US$1,000 with most in the US$500 to US$700 range.
Acer Iconia tablets
The PackardBell Butterfly
Asus T101 MT - they have a couple in the series
Vye Mini-v S37 and the S41
There may well be others out there that I didn't find in those few minutes of searching. yes, most of these are a bit heavier than the Microsoft Surface, have a stronger case, a full blown keyboard, and about the same money or less. Many have larger hard drives, dvd drives, upgradeable RAM, and are cheaper and available on the shelves right now.
The only thing new that Microsoft are doing with the tablet is providing the soft keyboard as against a hard keyboard and using titanium to make it lighter. I wonder how the weight vs durability argument goes with users?