all colors are not created equal...I am assuming you are talking a two stage base clear.
Some colors cover good in 3 coats with the correct color under coat, some can take 10 or more especially if you get fancy.
Jams and engine bays suck up lots of paint due to the amount of angles and surface area.

Without specific info and doing a sprayout calculating the amount of basecoat is hard.
some base coats can run upwards of $200 a pint
I would assume you would need about 6qt of mixed clear to do the exterior.
A good custom shop the price would start at at least 5,000 to paint it. again it depends on color,effects,jams,engine bay, and expected quality. You can easily spend 30k on a full custom show quality paint job....
hope this helps.