I wonder how you would do just calling school districts and ask them if they are getting rid of any.
The guy I picked mine up from said the district got 10 new busses the year I bought mine. He said they usually just drive them to the scrap yard. Prices were so low for scrap they decided to try to sell them.
You wouldn't have to pay a buyers premium and you wouldn't be bidding against anyone.
Might be worth an afternoon on the phone.