Unfortunately, accessory makers don't like having a bunch of dead stock, so they wait to see if the Surface line sells at levels enough to make it worth their while. With the recent announcement that the Surface products as a whole has lost 1.7 billion dollars (excluding salaries) since the initial launch, they're not all clamoring to get products out the door.
I am surprised that
Incipio is so far just offering a sleeve, but the fact that the link at their site says '
Surface Pro 3 Cases' is hopeful.
Maroo has some cases, but they're ugly and have that dreaded elastic band to hold the keyboard in place. They're also quite bulky, but look to have ample padding if you need some sort of protection right away.
You can also search
Amazon, but virtually all they have so far are the kind that extend over the bezel and look a lot like the Maroo ones. Keep an eye out for a
Freedom Case for the SP3, a well designed case for the SP1/2 with a lot of thought to form & function, and it doesn't extend over the bezel.