Though Sigma has received a bad rep in the past, I have to admit that the quality of their lenses in the past year has drastically improved: especially with their primes.
With that said, B&H Photo currently has discounts on a bunch of their lenses. The ones that you’ll probably care about the most are the 105mm f2.8 and 70-200mm f2.8 EX: both of which were reviewed on this site.
But they also have the Bower 24mm f1.4 in stock, which is the same thing as the Rokinon 24mm f1.4. Again, we implore you to check out our review before you purchase.