Rare Items:

-A stack of cacti for 5k, or $100 per cacti

Tools:

Selling a lot of regular and efficiency 1 diamond tools

Gems/Ores:

Emeralds on sale for $250 each

Rooms:

-2 Penthouses for 10k each
-Apartments in complex E&F of apartment block in Caprica for 3.5k each
-Apartments in complex A-D of apartment block for 4k each
-$500 extra for interior decoration

Rooms inside the Titanic (Preordering/Donations:)

-$20,000 for deluxe, sternside room
-$15,000 for a first class
-$10,000 for a second class
-$5,000 for a third class

Ultimate: A large, 50x65 block of prime real estate on the Titanic on sale for 100k, can turn out over 140k if you have a good business mind

 

Sure, I'll take some screenshots and post them on this thread when I'm not too lazy :p