If you can get the hook up from your friend's dad on paint...could you rent a spray gun from somewhere? I've heard rumors about places renting autopaint guns (lower pressure, finer mist). Then if you could rent the gun, and your friends dad is a paint guy, perhaps you could get him to go one more and help you paint it.
lay down alot of drop cloths and open a window!
but who knows, you might be able to pull it off, and it would be cheaper. Me thinks that a body shop, at least the more reputable ones, would not want to use the paint you buy from outside, liability reasons and such.
either way, good luck
-wheel