I did the 1 day M school that Paul described with the BMWCCA and had a great time. In total I spent about $1,000 including gas, food, hotel and the school. Caravaned down and back with other club members, met a lot of cool people, and will definately do it again.
I have also been to the HPDEs with the NCC at Summit Point and they are excellent. They are very well organized and every instructor I've encountered has been great. I'll absolutely be at all of them again this year because like Paul said, you're in your own car with your own instructor. You learn a lot more in those two days than at the 2 day M school.
I'm not trying to talk you out of the 2 day M school but for the same amount you can do the NCC 1 day school and two, maybe 3, NCC Summit Point events.