Generally speaking the price of a processor is going to be the square of the single threaded performance times the number of cores. So your choice is more like

Generally speaking the price of a processor is going to be the square of the single threaded performance times the number of cores. So your choice is more like one 8 GHz core versus 4 4GHz cores. Which might be good or bad depending on your use case. Well, there's a threshold below which you only get linear per-core scaling but outside microcontrollers you're not going to have to worry about that.