Search for red sport deals on here, I’ve seen many at $500 per month or less with zero down. At s minimum use those posted deals to see how close your dealer can get. Better yet, check with some of the brokers on here that regularly post Infiniti deals. I bet they can beat those numbers.
Just noticed your mileage requirements are 18K per year, where most of the deals I’ve seen were 10-15K, so probably not going to see sub $500 payment. Without doing the calculations, I would still think there is some decent room to negotiate your current lease offer.