Use the following trick to get 20,000 in coin, wood, and food for the single player
campaigns. Start your campaign and save the game immediately when it starts. Click 
"Menu", resign, and go back to the game play menu. Select "Single Player", then 
"Skirmish", and start a new Skirmish mode game. The skirmish will begin with 20,000
in all three resources. Click "Menu", then "Load", then choose the Campaign mode game
that you just saved. The game will resume with your resources at 20,000 each.