First, :welcome: to DC sti! Glad to have you here!
Your dad has excellent taste in cars! :bigups I agree with Dave:
It "should" be based on how much work is involved, not what type of car it is and how much it's worth. From their experience, they have a general idea how long it will take them to complete. If the same amount of work is put in, then I would expect them to charge similar amounts.
I don't know this guy or his skill level, but an expensive wax does not make a good detailer. The prep of the paint will be 90% or so of the "look" of the car. You aren't going to put a "miracle" wax on an improperly prepped car and have it look good.
Anyways, here is where the differences lie. Most clients that have very nice cars will spend the extra money to have the detailer take the time to do every little detail. And I mean EVERY detail. A good friend of mine does details like that where we will polish each individual bolt head in the engine compartment. These are for guys that compete at shows under the microscope. Hardly a logical choice for a daily driver. These types of clients want perfection and are willing to pay for it. It would not make sense to spend that amount of time and money on your daily driver, as it would be exposed to daily incidents. Did the detailer understand that you didn't want a full blown detail?
Either way, why not just learn to do it yourself? It will save you a lot of money and give you the satisfaction of doing it yourself.