Well I was going to suggest Lodge, but I just went to their web site and can't find the non-seasoned stuff anymore.
Out of curiosity, why do you want non-seasoned? Is there something bad about them? You'll need to season it before you use it though. I inherited all my cast iron so it had been used for years before I got it so I've never bought new, but I've been eying a
Lodge grill pan for a while.