If i am going to lease a Infiniti G37 and i wanted to the premium package How much more would it be per month?

http://infiniti.com/

It all depends on your credit.

Probably like over 500 may be. Or I'd just use lease calculator on their website. Most car company website offer payment calculator for buying/leasing.

Probably not more than $30 extra per month. But it depends on the term of your lease, the bottom line price, your credit, and your APR.

Lets put it this way.. if you are lucky and catch a deal you could lease one for $499/month for 39 months (with a 10% downpayment of course). With this situation, you would be better off purchasing the car or financing one (they do retain value, unlike previous Infiniti models).