NJ is expensive in that

both property tax and state income tax(almost no deduction at all) are high. In addition, people making money in the city share the resources with New Jersey residents. Obviously, NYC doesn't lack wealthy people:)

If you want to buy a house for 3 people family in a good district, you have to make your budget above $550K. That usually means you have to pay $3500-4000 each month.

The commute is also costly. Auto insurance here is high. The traffic is terrible. If you join the public transportation, $150 each month is a low budget.