This is on reddit right now and I thought I would share it with gamefaqs....
You can buy your properties without a loss of money. You will need enough money to afford the property but it won't cost a dime...
Go to the property you wish to purchase and buy it like normal.
As soon as you buy it and the quick cutscene starts pause the game and replay a mission.
Pick a short or easy one.
You must complete the mission.
As soon as you finish the mission you will be transported to the front of the business and you will see that its been purchased. If you check your pause screen you will see that you DIDNT SPEND A DIME!
Its cheap and game breaking but with the return on your investment being so low on businesses this is an option!