Using Art Money software, you can hack/edit in-game money. Try this steps (any damage/game crash is your responsibility):-
1. Get Art Money
here, install and run.
2. Run ra2.exe (Red Alert 2 executable).
3. Get into the game (campaign or skirmish), wait until the money is static.
4. Use Alt+Tab to get to Art Money, select process (Red Alert 2), click Search and enter the money value.
5. Get back to Red Alert 2 using Alt+Tab, select something to build, wait a second then right click to hold the build. Look at the current money and get back to Art Money by using Alt+Tab.
6. Click Filter and enter the current money value.
7. Now Art Money find 3 addresses, click Add All and modified the value as you want. I always make it 999999 :-)