If you use IB it is around $10 per month for the subscription and the ability to trade most US stocks which includes the Nasdaq. If you do more than $30 worth of commission in trades then the $10 is waived.
If you want to subscribe to Nasdaq Level II then it depends on your broker. IB charge $79 per month just for the data which in my view is very expensive as you can get it much cheaper than that. Investin charge around $125 for their DAE Level II platform which includes the exchange fee but again is waived if you do a certain amount in commissions.
I am pretty sure that the actual exchange fee is around $1 but I am sure someone will correct me if wrong.