S.W.
I suggest you read more about Montessori method and philosophy before you start looking for schools. It may not be the perfect match for your daughter! Start visiting schools to observe classes! Montessori are not always more expensive than normal preschools.
Here's a website that can help you find out more about their philosophy:
http://www.montessori-intl.org/philosophy.html
You can find Montessori schools that are fully accredited by the American Montessori Society through their website: http://www.amshq.org/
Our daughter will start preschool next year when she turns 3, we visited few schools already, and made our decision just last week! Good luck!