From the campaign:
We have added terrain and Battle Mat as Add-ons. We also clarified and posted in the FAQ section how the shipping costs works.
"The maximum shipping charge for a combined pledge/add-on set is $60. If summed shipping charges from all your pledges/add-on exceed this amount you pay only a maximum of $60 for the P&P."
p.s. Harbor pledge includes one Ware Piles set, we missed that in the pledge description and we cannot edit it now.