kasinkei

Not necessary. when you are financing with retained earnings (i.e., you are not asking for NEW capital), you are using capital from whatever EXISTING sources of capital you are using, so if your capital structure has debt/bond (i.e., you have financed your operations with debt/bond), you have to weight the cost of debt as well in your WACC. If you are like some of the high tech companies who do not use debt, then it is correct what you said since weight of debt =0.