Sure. Blue is definitely a Rock color, and there are definitely lines of bantams.
Sadly I do not know of a breeder for you off the top of my head. I do know that Cackle Hatchery and My Pet Chicken sell bantam Barreds.
If you are a bit industrious, you could start with Blue Rocks and breed down to bantam. It's not hard to get bantam size once you introduce the smaller genes.
Or, a little more effort, start with the Barred bantams and breed to blue (from a standard Blue).