Harvester Mining Drone
From Backstage Lore Wiki
A specialized mining drones that yields an extra five cubic meters per cycle over its tech 2 cousin, at the expense of going only half as fast. Most miners forgo them for their questionable utility and exorbitant price.
The only source that existed for the Harvester drone was from killing NPC convoys that went from station to station, a tricky activity. One of the random drops from these killed freighters would be these drones. However some time ago (exact date unknown) they stopped being dropped from said convoys. As normal attrition continued, these drones became rarer and rarer, shoving the price up. Nowadays they're only kept as collectable items or used by particularily unbalanced miners.