a)Taking your kid out of public school and
b)Encourage your kid to do things he finds interesting with you at home and take him to museums and crap
True, it requires a mostly unemployed parent, but Montessori has just discovered how kids learn naturally at a young age. Just like a kid learns a language without having to be formally taught, he learns other things without formal education as well. The older years it's a different story, but there's really no need to pay a ton of money for a Montessori pre-school. Any parent can do it.