With DoF not being controllable, how 'fast' can you expect? Yes, folks shoot f1.2 lenses wide open, but to limit it like that just doesn't work for sales. Besides, unless you're looking for pressed glass elements, not the ground to perfection elements, you're never going to get the quality image. Third party folks are getting better, but in the end the actual cost of r&d, materials and licensed technology - forget making a profit - makes this impossible.
Speed, length, quality and price - pick 2, and the others will give you options.