If you don't intend to use tablet mode:
I use this one and get on alright with it:
Plus a whole bunch of other 12" memory foam padded ones you can buy for peanuts :)
Order some 3M vinyl from Amazon and just wrap that thing yourself. I'm thinking about doing the same but I might buy this case instead after seeing a post here about the bottom.half of the case, unofficially, doubling as a keyboard cover. mCover case ($21.99)