I too am starting my journey with a skoolie. I'm one step ahead, though - I just bought my school bus.
Facebook marketplace was where I got mine, and it was a pretty good resource for me. Craigslist would also be a good place to look, as well as government auction sites like https://www.publicsurplus.com/
Otherwise, this website is a fantastic resource! I have learned so much in the two months I've been around. Welcome to the forums!