Another easy say to get Simoleons if you have Seasons that I haven't seen anybody mention is the Harvest Day Gnomes. After you appease the Gnomes place them in your household inventory. They will conveniently generate seed packets straight into your inventory making them easy to sell. I've earned thousands that way

Quantum entanglement and the Geth. Have a quantum entangled group of Geth stowaway on the Quarian ship with the entangled group "hibernating" in a secret Milky Way base were they are in waiting on the wake up signal from Andromeda. Have Liara detect the wake up signal and go searching for the Milky Way Geth base.