just be aware that auto-shop painters are great at painting METAL panels....when it comes to a wooden box it can potentially look crap unless you put a lot of time bogging/sanding the outer cabinet to perfection.....THEN their spraying techniques will show nicely.

Otherwise consider some form of furniture sprayer which knows how to treat/paint wood products better than auto-shop guys would...there might be a bunch of preps & pre-coats by the furniture guy that the auto-guy might not consider...

my 2c.