Alter your game files at your own risk and ALWAYS make backups. Access the Data folder on your computer, which is usually located at
C:/.... Airlines 2/Data or similar. Open the Magic.txt file in a text editor such as Notepad. Then type in INTEGERBE_INITIAL_CASH#########
where the '#' characters are digits to indicate the amount of money with which you wish to begin play. Save the document and load the new game to find that you have that same amount of money available.