best places to buy a school bus?

You can probably find used shuttle buses. Try test driving one. They're absolute bears. A full size school bus is both cumbersome and a drinks gas by the truckload. tey Facebook marketplace or a commercial truck salesman.

I have no idea, but I applaud your decision! How cool!

Check with your county. They usually auctions off all county vehicles when they leave service. This includes school busses.

They are typically not for sale, but instead are usually dismantled and recycled at the end of their life cycle.