$600 to sand/soda blast eng compartment and underside?

Sounds like you don't know your body man very well.Or perhaps you didn't discuss the level of finish that was or is expected.What is involved? Will he move your car to his shop,blast then return to the original shop? All this takes time and money.Too many times we say-thats cheap,or thats too expensive without knowing the background.Enlighten us a little and we can give you a more educated opinion.