how much should a complete valve job cost both sides and resurfacing using all dealership parts?

What size engine? I haven't had to have one done lately, but last time I did, it was about $100 or so, per head. You should also have the block checked and decked if necessary.

he's quoting way more than that in parts and still need to be surfaced

Then he is most likely replacing the valves, seats, and springs, without determining whether or not they need to be replaced. Usually, valves and seats can be ground and valve springs usually only need to be replaced when they break.