Your econ prof said that there was no such thing as price gouging because the free movement of prices also changes the relationship of supply and demand. For instance, a supplier of a good raises his prices too high, demand for that good will decrease, and his business will suffer. In the Dell example, this is happening with HoundDog; he has decided that the price of the power supply is too high and he will not be buying from Dell any more. If enough consumers come to this reality, then Dell will lose many more customers as a result of this and it will hurt their bottom line; they will be forced to lower the price of this component (assuming that this is the only reason for the loss of business) in order to get their business back. However, if there is an alternative (HP IBM ect) gouging probably cannot exist because the consumer has a choice and can go elsewhere.
The Ferrari is definitely not a gouging example because competition exists in the luxury sports car market. If one Ferrari dealer was charging 2x more than another dealer simply because of location or some other factor, this would be an example of a form of price gouging.