need to know what the normal cost is for borrowing money from a friend for a rehab.

[Waylon Bruce Moore]

We normally have been using our cash to buy, reno, and hold houses for rentals. Recently, my neighbor approached us about buying her home. It needs extensive renovations, and we would probably flip it once finished. There is a return of about 16% and annualized 33%. one of my close friends recently offered to fund any projects we were going to do and since i dont have much expereince in getting loans what is the normal return i should offer them for a loan of about 400k over a 6 month time frame (purchase-reno-sale)?