You are sharply underestimating per-deal sizes for enterprise sales. $200 a class isn't so much to actually make $200 a class. $200 just establishes an anchor such that the school district demands a discount and you say "Alright, with 500 teachers teaching 4 classes each, we can let you have this for only $350,000 a year. That's a huge discount off our list price."

Welcome solidly to Enterprise Sales if you adopt this path, which has it's own set of challenges vs. e.g. selling to teachers directly. There are quite a few enterprise software companies which make good money. Some of them even produce good software, too.