How much should my Private Money charge me to fund my Flips?

[Roberto Lopez]

I am on the verge of accepting private money from friends and family who trust me and know the capability of the business. I am struggling to understand just how much I should be charged for the private money. They aren't really RE investors but want to invest through me. Is there an "Average" percentage I should be paying them for their money or should I pay them a high return so they can stay motivated and keep investing in RE through me?