Utilises a glitch with a bug concerning reverse thrust on jet engine.
Reverse Engine Bug:
Add a jet engine to craft.
Add/remove reverse thrust in the Part Property. The price will not update on the Part Property nor the Design info.
If you move the engine (which doesn't update the price) and then press undo, the price now updates on both Part Property and Design Info. Essentially, pressing undo undoes the reverse thrust change and corrects the price
Infinite Money Glitch
Take note of Current Money.
Do the steps above so the engine doesn't have reverse thrust, and the price is the unglitched price (press undo to correct price).
On the part properties, now add reverse thrust, and don't press undo, hence getting the reverse thrust for free.
Launch craft on Juno village. The engine will have reverse thrust capability.
Recover craft and the recovery will be more than launch cost, as exemplified in the save file. The recovery fee will assume you paid for the reverse thrust.
Look at Current Money. Should have increased.