If you are after a rough idea, from a high end custom shop?
My car has heaps of coats of paint, it has been a few different colours, maybe it was used for bank jobs?
To bare metal it, and make it perfect, in a custom paint, $15k drive in/out, as a paying job (ie, not at mates rates, where it takes 3 years to go nowhere, and they have to redo what they did at the start, because it has taken so long).
I settled for a couple of coats of primer, and a layer of colour, and 2 of clear, for about 1/2 that.