Jetpack

The Steampunker only lists it on certain moon phases, so an empty shop tonight is not a bug. Sleep through a night or two and check again. Gold is rarely the barrier here, the calendar is.

Flight time is short next to other wings of the same era, but it climbs like nothing else at that stage. Holding up while airborne throws you upward far faster than any wing can manage, at the cost of draining the tank twice as quickly. That trade pays off in fights that need you to gain height in a hurry, the Twins especially, and it is the wrong tool for a long trip across the map.

The habit worth building is tapping the boost in short bursts instead of holding it down. You get most of the height and keep enough fuel to land somewhere you chose.