I agree with the posters who say you have to consider your financial situation carefully. Also as another mom said.... be wary of "montessori-based" curriculums, they are NOT the same thing.
That being said, my daughter attends a Montessori school and we love it. I can't speak for NJ, but the cost in Chicago for private accredited Montessori will range from $8,000 - $12,000. Although some do have financial aid or 'sliding' scale tuition, so you should check with your school office. It is a financial committment for a good number of years (most start at 3yrs old and go until your child goes to high school.
The basis of a Montessori school is self-motivation regarding inquisitiveness, self-care and helping each other. These are things that Public Schools (who generally 'podium teach' - ie: teach the same thing to a large group of students and aim for the 'middle' as far as level of teaching).
Beware, though!!!!! Only send your child to a Montessori school if you want them to be a free-thinker who is able to make good decisions on their own!!!! I responded to another question about Montessori and had a mom private message me that she HATED when her son when to Montesorri school because it made him "hard to manage" at home - he no longer just did whatever she told him to do, instead he wanted to take care of himself and ask questions!!!!!!! The nerve of that child being a free-thinker!!!!!
Montessori schools are structured so that each child has a 'work plan' and then can make decisions about how they accomplish their 'work' for the week. Montessori schools teach kids how to prioritize and make decisions for themselves. Kids who attend Montessori schools are usually extrememly high achievers in all areas. My daughter is in the 4th grade and she is well above the kids her age from the neighborhood in math - mostly because she has developed critical thinking skills as well as the ability to apply reason and logic to situations. But that's not all Montessori schools, so check out where the graduates of the school you are looking at go to High School.
I will tell you that some of the curiculum is called "Life-Based Learning" - the public schools in Chicago use "everyday math" which is basically the same concept. So, you learn fractions by discussions situations they actually encounter on a daily basis rather than "train A leaves the station at 1:30 going 60 mph....." that we could never relate to as kids!!!!!! Anyway kids sometimes don't bring home homework that parents can readily identify as "homework" because it's not a list of mulitplication tables to memorize. The kids learned fractions in 1st grade by helping to make breakfast "if each child gets 2 eggs and we have 5 eating breakfast, how many eggs do we need?" that sort of thing rather than "memorize this worksheet of information - it will be on a test".
Good luck with your decision. My daughter attended public school and then transferred into a Montessori school so she wasn't there for the early childhood program. I personally wouldn't want her anywhere else because I see the impact that the Montessori teaching method has on her every day behavior, outlook and self-esteem.