I did the same liner install and it ran me about $500 with insulation.  I chose to insulate because my chimney's outside the wall of my house, and only about 15' tall so draft may have been an issue.
I've got to ask: What's with the block off plate on the bottom? If the top plate is sealed won't that stop any draft? I could see if you wanted cold air not to roll down when the fireplace isn't being used but was it just for cleaner install?
	
		
			
		
		
	
				
			I've got to ask: What's with the block off plate on the bottom? If the top plate is sealed won't that stop any draft? I could see if you wanted cold air not to roll down when the fireplace isn't being used but was it just for cleaner install?