WARTILE

You need to complete all missions up to the Rescue board mission to unlock the option to purchase all 4 additional figurines. I believe the last figurine, Ivor, costs 650 gold to unlock but if you have been opening chests as you went and completing the missions you should have more than enough gold to unlock all the figurines.

You can also sells duplicates of items you don't need at the shop to earn some extra gold if need be.