> Presumably PRC and Russia were supporting this industry either directly

Not during development/early phases, they were created during time where sanctions were somewhat enforced. Debris analysis of earlier models show they were full of western COTs parts, including stripped components, i.e. think RU breaking washing machine for chips. Incidentally they were also fairly expensive, 4 digits, for otherwise a rudimentary - though elegantly simple form factor. At least given sanction constraints and relative to what Iran industrial base can muster at relative scale.

Realistically the BOM for one of these things should be low $1000s if value engineered by competent industrial power like PRC. Who has contract to acquire 1m loitering munitions/drones this/next year. There's have factories that can churn millions of of engines per year, i.e. 10s of 10000s of 1500-2500km fires per day.