I think most private schools are in that range of costs/year too, so I doubt there is much to gain by doing this. Plus it would be a logistics nightmare. I wouldn't want to interview teachers for all my kids each year as they move up in classes. Then transport them myself to multiple locations and back each day. Plus they would lose the ability to do specialized classes like music, art, and shop. I doubt that would be any more cost efficient anyway; you are ignoring the overhead of a building, computers, labs, supplies, gymnasium, playground, lunchroom, etc... Public and private schools are intentionally co-locate classed together to take advantage of sharing those things.