There are many properties to buy. As you buy more land and properties, the price of them will increase. It is smart to buy in groups of 10 at a time because of the increase in price every time you buy properties.
Below is a list land and properties that are available in-game.
LAND
Industrial Field Income: $500 Initial Cost: $50,000 Available at Level: 1
Ocean Platform Income: $3,000 Initial Cost: $500,000 Available at Level: 10
PROPERTIES
Mutant Laboratory Developed on: Industrial Field Income: $3,000 Initial Cost: $100,000 Available at Level: 1
Experimental Weapons Facility Developed on: Industrial Field Income: $10,000 Initial Cost: $500,000 Available at Level: 1
Offshore Drilling Facility Developed On: Ocean Platform Income: $35,000 Initial Cost: $2 Million Available at Level: 10
Combat Training Dome Developed On: Ocean Platform Income: $115,000 Initial Cost: $10 Million Available at Level: 20