I agree... but it all depend on the situation. For example, existing power grid, including conventional power plant can take 20% or 30% of intermittent power with close to no extra cost... And the energy mix, the interconnections, the location, the consumption habits all have an impact on the price. Simulation at a grid level, including demand response, thermal storage... can give some precise ideas.

Note that for doing apple to apple we should also include positive and negative externalities