Not a big discount but a discount it is, the Nikon version of the Tokina 100mm f2.8 AT-X PRO D lens is available for $350 after a $20 mail-in rebate (MIR) at Adorama. You also receive $15~ in promotional rewards to be used in future purchases at Adorama. The mail-in rebates expire 12/31/16.
One of the benefits of Canon/Nikon SLR systems is the abundance of 3rd-party lens options, from the perspective of photographers of other systems lamenting the lack of choices. On the other hand, it makes picking lenses easier 🙂