I remember looking into Montessori schools for my kids and found them to be quite expensive. On one of their web pages they attempted to justify the cost by saying that the children would have access to very nice furniture.
For every legitimate school there seems to be another which is just a cash grab.
Ours is on the lower end of private school prices for our area (around $1200/month,) but it is a non-profit. That brings its own set of challenges, but keeps costs down. Top private schools in my area are more than $3k/month, for reference.
I mean, I don't know what types of prices we're talking about, but running schools is expensive, so when you aren't government-funded you have to charge a lot.
For every legitimate school there seems to be another which is just a cash grab.