You do not need the enterprise license to run this self-hosted, only if you want the commercial license version of AGPLv3 + support/SLA and some high scale plugins like our dependency cache syncing.
Your calculation is correct and I agree it is a bit of a steep pricing. Most companies have small scripts to run and we wanted to bill according to the value they were extracting of the product and do transparent enterprise pricing instead of the usual "contact us". Unfortunately, it is not a one-size-fits-all situation. For data heavy/IO bound workflows, we should bill per number of GB transferred rather than per computation. In any case, we are very open to do price capped contracts depending on your use case: ruben@windmill.dev