They could conceivably be very cheap if the gas pockets were mass produced. Everything else on board for propulsion and housing the pilot would be on the scale of a small prop aircraft. As long as the cargo can be easily managed, perhaps in a shipping container, then these would be easy to deploy en masse. They can land in any suitable field that has a crew on hand to guide them in with ropes. You might not even need pilots since these would be perfect targets for automation.
As for speed, you can optimize the shape of the aircraft and the position of the propeller for this. I've seen a number of videos that show surprisingly good performance for pointier fuselage with a pusher prop on the tail.
> Everything else on board for propulsion and housing the pilot would be on the scale of a small prop aircraft
It's likely that any cargo airship would fly for days/weeks at a time and would require at least 4 crew-members and everything they would need for the length of the voyage. So less a small prop and more something akin to facilities available on a yacht/Large RV.
> You might not even need pilots since these would be perfect targets for automation.
As for speed, you can optimize the shape of the aircraft and the position of the propeller for this. I've seen a number of videos that show surprisingly good performance for pointier fuselage with a pusher prop on the tail.