The Sims Medieval, similar to previous versions, has a money cheat you can enter to get 50,000 simoleons every time.
Hit Ctrl+Shift+C to bring up the command prompt. Type in motherlode and hit enter to get 50,000 simoleons, or type in Kaching for 1,000 simoleons if you want to cheat, but not too much.
You can enter these cheats as many times as you want.