Cheat Engine 5.5 will allow you to edit any variable (Money, Stats, Relationships, etc...) during game play. It's not specifically built for any game but can pinpoint precisely where it is you want to modify and even give you the option to lock the value in so it cannot change

Very easy to use, I targeted money because frankly I was tired of motherlode cheat.

1. Load TS3 if not already loaded
2. Load up a game and write down current money
3. Press Alt+Tab or Win+Key to minimize to desktop if full screen
4. Load Cheat Engine 5.5
5. Click Processes and TS3.exe
6. Type in current money (without commas) leaving all else as is and press First Scan
7. You'll see a list of the results on the side maybe a lot or a few
8. Go back into the game and buy something
9. Go back to Cheat Engine and under the drop down select decreased value and next scan
10. If you haven't narrowed down to one item go ahead and use motherlode cheat in-game and select increased value and find next
11. Once you have it down to one item double click to place in bottom area and select freeze, changes happen immediately
12. Right-click and select change record and value, just type 999999 or whatever and ok, don't worry about any messages that may or may not come up about digit changing, this is money and don't add -0 at end if it asks you

Go into game and buy whatever without worry of losing money, after first purchase you'll see the update of your money, save game if desired and money will stick